# 4.3: Rules for Exponents (2023)

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Learning Objectives

• Product and Quotient Rules
• Use the product rule to multiply exponential expressions
• Use the quotient rule to divide exponential expressions
• The Power Rule for Exponents
• Use the power rule to simplify expressions involving products, quotients, and exponents
• Negative and Zero Exponents
• Define and use the zero exponent rule
• Define and use the negative exponent rule
• Simplify Expressions Using the Exponent Rules
• Simplify expressions using a combination of the exponent rules
• Simplify compound exponential expressions with negative exponents

Repeated Image

## Anatomy of exponential terms

We use exponential notation to write repeated multiplication. For example $$10^{3}$$. The 10 in $$10^{3}$$ is called the exponent. The expression $$10^{3}$$ is called the exponential expression. Knowing the names for the parts of an exponential expression or term will help you learn how to perform mathematical operations on them.

$$\text{base}\rightarrow10^{3\leftarrow\text{exponent}}$$

$$10\cdot10\cdot10$$, or 1,000.

$$8\cdot8$$, or 64.

$$5\cdot5\cdot5\cdot5$$, or 625.

$${b}\cdot{b}\cdot{b}\cdot{b}\cdot{b}$$. Its value will depend on the value of b.

The exponent applies only to the number that it is next to. Therefore, in the expression $$xy^{4}$$ means $${x}\cdot{y}\cdot{y}\cdot{y}\cdot{y}$$. The x in this term is a coefficient of y.

If the exponential expression is negative, such as $$–\left(3\cdot3\cdot3\cdot3\right)$$ or $$−81$$.

If $$\left(−3\right)^{4}$$, which means $$−3\cdot−3\cdot−3\cdot−3$$, or 81.

Likewise, $$−x^{4}=–\left(x\cdot x\cdot x\cdot x\right)$$.

You can see that there is quite a difference, so you have to be very careful! The following examples show how to identify the base and the exponent, as well as how to identify the expanded and exponential format of writing repeated multiplication.

Example

Identify the exponent and the base in the following terms, then simplify:

1. $$7^{2}$$
2. $${\left(\frac{1}{2}\right)}^{3}$$
3. $$2x^{3}$$
4. $$\left(-5\right)^{2}$$

1) $$7^{2}$$

The exponent in this term is 2 and the base is 7. To simplify, expand the term: $$7^{2}=7\cdot{7}=49$$

2) $${\left(\frac{1}{2}\right)}^{3}$$

The exponent on this term is 3, and the base is $${\left(\frac{1}{2}\right)}^{3}=\frac{1}{2}\cdot{\frac{1}{2}}\cdot{\frac{1}{2}}=\frac{1}{16}$$

3) $$2x^{3}$$

The exponent on this term is 3, and the base is x, the 2 is not getting the exponent because there are no parentheses that tell us it is. This term is in its most simplified form.

4) $$\left(-5\right)^{2}$$

The exponent on this terms is 2 and the base is $$\left(-5\right)^{2}=-5\cdot{-5}=25$$

In the following video you are provided more examples of applying exponents to various bases.

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### Evaluate expressions

Evaluating expressions containing exponents is the same as evaluating the linear expressions from earlier in the course. You substitute the value of the variable into the expression and simplify.

You can use the order of operations to evaluate the expressions containing exponents. First, evaluate anything in Parentheses or grouping symbols. Next, look for Exponents, followed by Multiplication and Division (reading from left to right), and lastly, Addition and Subtraction (again, reading from left to right).

So, when you evaluate the expression $$x=4$$, first substitute the value 4 for the variable x. Then evaluate, using order of operations.

### Example

Evaluate $$x=4$$.

Substitute 4 for the variable x.

$$5\cdot4^{3}$$

Evaluate $$4^{3}$$. Multiply.

$$5\left(4\cdot4\cdot4\right)=5\cdot64=320$$

$$x=4$$

In the example below, notice the how adding parentheses can change the outcome when you are simplifying terms with exponents.

### Example

Evaluate $$x=4$$.

[hidden-answer a=”362021″]Substitute 4 for the variable x.

$$\left(5\cdot4\right)3$$

Multiply inside the parentheses, then apply the exponent—following the rules of PEMDAS.

$$20^{3}$$

Evaluate $$20^{3}$$.

$$20\cdot20\cdot20=8,000$$

$$x=4$$

The addition of parentheses made quite a difference! Parentheses allow you to apply an exponent to variables or numbers that are multiplied, divided, added, or subtracted to each other.

### Example

Evaluate $$x=−4$$.

[hidden-answer a=”86290″]Substitute $$−4$$ for the variable x.

$$\left(−4\right)^{3}$$

Evaluate. Note how placing parentheses around the $$−4$$ means the negative sign also gets multiplied.

$$−4\cdot−4\cdot−4$$

Multiply.

$$−4\cdot−4\cdot−4=−64$$

$$x=−4$$

Caution! Whether to include a negative sign as part of a base or not often leads to confusion. To clarify whether a negative sign is applied before or after the exponent, here is an example.

What is the difference in the way you would evaluate these two terms?

1. $$-{3}^{2}$$
2. $${\left(-3\right)}^{2}$$

To evaluate 1), you would apply the exponent to the three first, then apply the negative sign last, like this:

$$\begin{array}{c}-\left({3}^{2}\right)\\=-\left(9\right) = -9\end{array}$$

To evaluate 2), you would apply the exponent to the 3 and the negative sign:

$$\begin{array}{c}{\left(-3\right)}^{2}\\=\left(-3\right)\cdot\left(-3\right)\\={ 9}\end{array}$$

The key to remembering this is to follow the order of operations. The first expression does not include parentheses so you would apply the exponent to the integer 3 first, then apply the negative sign. The second expression includes parentheses, so hopefully you will remember that the negative sign also gets squared.

In the next sections, you will learn how to simplify expressions that contain exponents. Come back to this page if you forget how to apply the order of operations to a term with exponents, or forget which is the base and which is the exponent!

In the following video you are provided with examples of evaluating exponential expressions for a given number.

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## Use the product rule to multiply exponential expressions

Exponential notation was developed to write repeated multiplication more efficiently. There are times when it is easier or faster to leave the expressions in exponential notation when multiplying or dividing. Let’s look at rules that will allow you to do this.

For example, the notation $$5\cdot5\cdot5\cdot5$$, or 625. And don’t forget, the exponent only applies to the number immediately to its left, unless there are parentheses.

What happens if you multiply two numbers in exponential form with the same base? Consider the expression $$\left(2\cdot2\cdot2\right)\left(2\cdot2\cdot2\cdot2\right)$$ or $$2^{7}$$. Notice that 7 is the sum of the original two exponents, 3 and 4.

What about $$\left(x\cdot{x}\right)\left(x\cdot{x}\cdot{x}\cdot{x}\cdot{x}\cdot{x}\right)=x\cdot{x}\cdot{x}\cdot{x}\cdot{x}\cdot{x}\cdot{x}\cdot{x}$$ or $$x^{8}$$. And, once again, 8 is the sum of the original two exponents. This concept can be generalized in the following way:

### The Product Rule for Exponents

For any number x and any integers a and b, $$\left(x^{a}\right)\left(x^{b}\right) = x^{a+b}$$.

To multiply exponential terms with the same base, add the exponents.

Caution! When you are reading mathematical rules, it is important to pay attention to the conditions on the rule. For example, when using the product rule, you may only apply it when the terms being multiplied have the same base and the exponents are integers. Conditions on mathematical rules are often given before the rule is stated, as in this example it says “For any number x, and any integers a and b.”

### Example

Simplify.

$$(a^{3})(a^{7})$$

[hidden-answer a=”356596″]The base of both exponents is a, so the product rule applies.

$$\left(a^{3}\right)\left(a^{7}\right)$$

Add the exponents with a common base.

$$a^{3+7}$$

$$\left(a^{3}\right)\left(a^{7}\right) = a^{10}$$

When multiplying more complicated terms, multiply the coefficients and then multiply the variables.

### Example

Simplify.

$$5a^{4}\cdot7a^{6}$$

[hidden-answer a=”215459″]Multiply the coefficients.

$$35\cdot{a}^{4}\cdot{a}^{6}$$

The base of both exponents is a, so the product rule applies. Add the exponents.

$$35\cdot{a}^{4+6}$$

Add the exponents with a common base.

$$35\cdot{a}^{10}$$

$$5a^{4}\cdot7a^{6}=35a^{10}$$

Caution! Do not try to apply this rule to sums.

Think about the expression $$\left(2+3\right)^{2}$$

Does $$2^{2}+3^{2}$$?

No, it does not because of the order of operations!

$$\left(2+3\right)^{2}=5^{2}=25$$

and

$$2^{2}+3^{2}=4+9=13$$

Therefore, you can only use this rule when the numbers inside the parentheses are being multiplied (or divided, as we will see next).

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## Use the quotient rule to divide exponential expressions

Let’s look at dividing terms containing exponential expressions. What happens if you divide two numbers in exponential form with the same base? Consider the following expression.

$$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/p[2]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/p[2]/span[2], line 1, column 3$$

You can rewrite the expression as: $$\displaystyle$$

Finally, this expression can be rewritten as $$4^{3}$$ using exponential notation. Notice that the exponent, 3, is the difference between the two exponents in the original expression, 5 and 2.

So, $$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/p[5]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/p[5]/span[2], line 1, column 3 =4^{5-2}=4^{3}$$.

Be careful that you subtract the exponent in the denominator from the exponent in the numerator.

So, to divide two exponential terms with the same base, subtract the exponents.

### The Quotient (Division) Rule for Exponents

For any non-zero number x and any integers a and b: $$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[1]/div/p/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[1]/div/p/span[2], line 1, column 3 = ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[1]/div/p/span[3], line 1, column 2$$

### Example

Evaluate. $$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[2]/p[1]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[2]/p[1]/span[2], line 1, column 3$$

[hidden-answer a=”96156″]These two exponents have the same base, 4. According to the Quotient Rule, you can subtract the power in the denominator from the power in the numerator.

$$\displaystyle ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[2]/p[3]/span, line 1, column 2$$

$$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[2]/div/p[1]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[2]/div/p[1]/span[2], line 1, column 3 =4^{5}$$

When dividing terms that also contain coefficients, divide the coefficients and then divide variable powers with the same base by subtracting the exponents.

### Example

Simplify. $$\displaystyle \frac{12 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[3]/p[1]/span, line 1, column 2 }{2x}$$

[hidden-answer a=”23604″]Separate into numerical and variable factors.

$$\displaystyle \left( \frac{12}{2} \right)\left( \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[3]/p[3]/span, line 1, column 3 {x} \right)$$

Since the bases of the exponents are the same, you can apply the Quotient Rule. Divide the coefficients and subtract the exponents of matching variables.

$$\displaystyle 6\left( ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[3]/p[5]/span, line 1, column 2 \right)$$

$$\displaystyle 6 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[5]/div[3]/div/p[1]/span, line 1, column 2$$

In the following video we show another example of how to use the quotient rule to divide exponential expressions

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## Raise powers to powers

Another word for exponent is power. You have likely seen or heard an example such as $$3^5$$ can be described as 3 raised to the 5th power. In this section we will further expand our capabilities with exponents. We will learn what to do when a term with a power is raised to another power, and what to do when two numbers or variables are multiplied and both are raised to an exponent. We will also learn what to do when numbers or variables that are divided are raised to a power. We will begin by raising powers to powers.

Let’s simplify $$5^2$$ and the exponent is 4, so you multiply $$\left(5^{2}\right)^{4}=5^{2}\cdot5^{2}\cdot5^{2}\cdot5^{2}=5^{8}$$ (using the Product Rule—add the exponents).

$$5^{8}$$. Notice that the new exponent is the same as the product of the original exponents: $$2\cdot4=8$$.

So, $$\left(5^{2}\right)^{4}=5^{2\cdot4}=5^{8}$$ (which equals 390,625, if you do the multiplication).

Likewise, $$\left(x^{4}\right)^{3}=x^{4\cdot3}=x^{12}$$

This leads to another rule for exponents—the Power Rule for Exponents. To simplify a power of a power, you multiply the exponents, keeping the base the same. For example, $$\left(2^{3}\right)^{5}=2^{15}$$.

### The Power Rule for Exponents

For any positive number x and integers a and b: $$\left(x^{a}\right)^{b}=x^{a\cdot{b}}$$.

Take a moment to contrast how this is different from the product rule for exponents found on the previous page.

### Example

Simplify $$6\left(c^{4}\right)^{2}$$.

[hidden-answer a=”841688″]Since you are raising a power to a power, apply the Power Rule and multiply exponents to simplify. The coefficient remains unchanged because it is outside of the parentheses.

$$6\left(c^{4}\right)^{2}$$

$$6\left(c^{4}\right)^{2}=6c^{8}$$

### Raise a product to a power

Simplify this expression.

$$\left(2a\right)^{4}=\left(2a\right)\left(2a\right)\left(2a\right)\left(2a\right)=\left(2\cdot2\cdot2\cdot2\right)\left(a\cdot{a}\cdot{a}\cdot{a}\cdot{a}\right)=\left(2^{4}\right)\left(a^{4}\right)=16a^{4}$$

Notice that the exponent is applied to each factor of 2a. So, we can eliminate the middle steps.

$$\begin{array}{l}\left(2a\right)^{4} = \left(2^{4}\right)\left(a^{4}\right)\text{, applying the }4\text{ to each factor, }2\text{ and }a\\\\\,\,\,\,\,\,\,\,\,\,\,\,\,=16a^{4}\end{array}$$

The product of two or more numbers raised to a power is equal to the product of each number raised to the same power.

### A Product Raised to a Power

For any nonzero numbers a and b and any integer x, $$\left(ab\right)^{x}=a^{x}\cdot{b^{x}}$$.

How is this rule different from the power raised to a power rule? How is it different from the product rule for exponents on the previous page?

### Example

Simplify. $$\left(2yz\right)^{6}$$

Apply the exponent to each number in the product.

$$2^{6}y^{6}z^{6}$$

$$\left(2yz\right)^{6}=64y^{6}z^{6}$$

If the variable has an exponent with it, use the Power Rule: multiply the exponents.

### Example

Simplify. $$\left(−7a^{4}b\right)^{2}$$

[hidden-answer a=”136794″]Apply the exponent 2 to each factor within the parentheses.

$$\left(−7\right)^{2}\left(a^{4}\right)^{2}\left(b\right)^{2}$$

Square the coefficient and use the Power Rule to square $$\left(a^{4}\right)^{2}$$.

$$49a^{4\cdot2}b^{2}$$

Simplify.

$$49a^{8}b^{2}$$

$$\left(-7a^{4}b\right)^{2}=49a^{8}b^{2}$$

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### Raise a quotient to a power

Now let’s look at what happens if you raise a quotient to a power. Remember that quotient means divide. Suppose you have $$\displaystyle \frac{3}{4}$$ and raise it to the 3rd power.

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You can see that raising the quotient to the power of 3 can also be written as the numerator (3) to the power of 3, and the denominator (4) to the power of 3.

Similarly, if you are using variables, the quotient raised to a power is equal to the numerator raised to the power over the denominator raised to power.

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When a quotient is raised to a power, you can apply the power to the numerator and denominator individually, as shown below.

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### A Quotient Raised to a Power

For any number a, any non-zero number b, and any integer x, $$\displaystyle {\left(\frac{a}{b}\right)}^{x}=\frac{a^{x}}{b^{x}}$$.

### Example

Simplify. $$\displaystyle ParseError: invalid DekiScript (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[1]/span, line 1, column 1$$

[hidden-answer a=”875425″]Apply the power to each factor individually.

$$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[3]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[3]/span[2], line 1, column 3$$

Separate into numerical and variable factors.

$$\displaystyle ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[5]/span[1], line 1, column 2 \cdot \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[5]/span[2], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[5]/span[3], line 1, column 3 \cdot \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[5]/span[4], line 1, column 3 {1}$$

Simplify by taking 2 to the third power and applying the Power and Quotient Rules for exponents—multiply and subtract the exponents of matching variables.

$$\displaystyle 8\cdot ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[7]/span[1], line 1, column 2 \cdot ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[7]/span[2], line 1, column 2$$

Simplify.

$$\displaystyle 8 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[9]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[6]/div[3]/div[4]/div[2]/p[9]/span[2], line 1, column 2$$

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In the following video you will be shown examples of simplifying quotients that are raised to a power.

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## Define and use the zero exponent rule

When we defined the quotient rule, we only worked with expressions like the following: $$\frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[7]/p/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[7]/p/span[2], line 1, column 3$$, where the exponent in the numerator (up) was greater than the one in the denominator (down), so the final exponent after simplifying was always a positive number, and greater than zero. In this section, we will explore what happens when we apply the quotient rule for exponents and get a negative or zero exponent.

### What if the exponent is zero?

To see how this is defined, let us begin with an example. We will use the idea that dividing any number by itself gives a result of 1.

$$\frac{t^{8}}{t^{8}}=\frac{\cancel{t^{8}}}{\cancel{t^{8}}}=1$$

If we were to simplify the original expression using the quotient rule, we would have

$$\frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[7]/div/p[4]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[7]/div/p[4]/span[2], line 1, column 2 ={t}^{8 - 8}={t}^{0}$$

If we equate the two answers, the result is $${t}^{0}=1$$. This is true for any nonzero real number, or any variable representing a real number.

$${a}^{0}=1$$

The sole exception is the expression $${0}^{0}$$. This appears later in more advanced courses, but for now, we will consider the value to be undefined, or DNE (Does Not Exist).

### Exponents of 0 or 1

Any number or variable raised to a power of 1 is the number itself.

$$n^{1}=n$$

Any non-zero number or variable raised to a power of 0 is equal to 1

$$n^{0}=1$$

The quantity $$0^{0}$$ is undefined.

As done previously, to evaluate expressions containing exponents of 0 or 1, substitute the value of the variable into the expression and simplify.

### Example

Evaluate $$x=9$$

[hidden-answer a=”324798″]Substitute 9 for the variable x.

$$2\cdot9^{0}$$

Evaluate $$9^{0}$$. Multiply.

$$2\cdot1=2$$

$$x=9$$

### Example

Simplify $$\frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[7]/div/div[4]/p[1]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[7]/div/div[4]/p[1]/span[2], line 1, column 2$$.

[hidden-answer a=”769979″]Use the quotient and zero exponent rules to simplify the expression.

$$\begin{array}\text{ }\frac{c^{3}}{c^{3}} \,\,\,= \,\,\,c^{3-3} \\ \,\,\,\,\,\,\,\,\,\,\,=\,\,\,c^{0} \\\,\,\,\,\,\,\,\,\,\,\,=\,\,\,1\end{array}$$

1

In the following video there is an example of evaluating an expression with an exponent of zero, as well as simplifying when you get a result of a zero exponent.

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## Define and use the negative exponent rule

We proposed another question at the beginning of this section. Given a quotient like $$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/p[1]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/p[1]/span[2], line 1, column 3$$ what happens when n is larger than m? We will need to use the negative rule of exponents to simplify the expression so that it is easier to understand.

Let’s look at an example to clarify this idea. Given the expression:

$$\frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/p[3]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/p[3]/span[2], line 1, column 2$$

Expand the numerator and denominator, all the terms in the numerator will cancel to 1, leaving two hs multiplied in the denominator, and a numerator of 1.

$$\begin{array}{l} \frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[1]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[1]/span[2], line 1, column 2 \,\,\,=\,\,\,\frac{h\cdot{h}\cdot{h}}{h\cdot{h}\cdot{h}\cdot{h}\cdot{h}} \\ \,\,\,\,\,\,\,\,\,\,\,=\,\,\,\frac{\cancel{h}\cdot \cancel{h}\cdot \cancel{h}}{\cancel{h}\cdot \cancel{h}\cdot \cancel{h}\cdot {h}\cdot {h}}\\\,\,\,\,\,\,\,\,\,\,\,=\,\,\,\frac{1}{h\cdot{h}}\\\,\,\,\,\,\,\,\,\,\,\,=\,\,\,\frac{1} ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[1]/span[3], line 1, column 2 \end{array}$$

We could have also applied the quotient rule from the last section, to obtain the following result:

$$\begin{array}{r}\frac{h^{3}}{h^{5}}\,\,\,=\,\,\,h^{3-5}\\\\=\,\,\,h^{-2}\,\,\end{array}$$

Putting the answers together, we have $${h}^{-2}=\frac{1} ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/p[7]/span, line 1, column 2$$. This is true when h, or any variable, is a real number and is not zero.

### The Negative Rule of Exponents

For any nonzero real number $$n$$, the negative rule of exponents states that

$${a}^{-n}=\frac{1} ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[2]/div/div/span, line 1, column 2$$

Let’s looks at some examples of how this rule applies under different circumstances.

### Example

Evaluate the expression $${4}^{-3}$$.

[hidden-answer a=”231258″]First, write the expression with positive exponents by putting the term with the negative exponent in the denominator.

$${4}^{-3} = \frac{1} ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[3]/p[3]/span, line 1, column 2 = \frac{1}{4\cdot4\cdot4}$$

Now that we have an expression that looks somewhat familiar.

$$\frac{1}{4\cdot4\cdot4} = \frac{1}{64}$$

$$\frac{1}{64}$$

### Example

Write $$\frac ParseError: invalid DekiScript (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[4]/p[1]/span[1], line 1, column 1 ParseError: invalid DekiScript (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[4]/p[1]/span[2], line 1, column 1$$ with positive exponents.

Use the quotient rule to subtract the exponents of terms with like bases.

$$\begin{array}{r}\frac ParseError: invalid DekiScript (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[4]/p[4]/span[1], line 1, column 1 ParseError: invalid DekiScript (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[4]/p[4]/span[2], line 1, column 1 ={t}^{3-8}\\={t}^{-5}\,\,\end{array}$$

Write the expression with positive exponents by putting the term with the negative exponent in the denominator.

$$=\frac{1} ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[4]/p[6]/span, line 1, column 2$$

$$\frac{1} ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[4]/div/p[1]/span, line 1, column 2$$

### Example

Simplify $${\left(\frac{1}{3}\right)}^{-2}$$.

[hidden-answer a=”998337″]Apply the power property of exponents.

$$\frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[3]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[3]/span[2], line 1, column 2$$

Write each term with a positive exponent, the numerator will go to the denominator and the denominator will go to the numerator.

$$\frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[5]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[5]/span[2], line 1, column 2 { = }\frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[5]/span[3], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[5]/span[4], line 1, column 2$$

Simplify.

$$\frac ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[7]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[8]/div[5]/p[7]/span[2], line 1, column 2 { = }\frac{9}{1}{ = }{9}$$

$$9$$

Example

Simplify.$$\frac{1}{4^{-2}}$$ Write your answer using positive exponents.

Write each term with a positive exponent, the denominator will go to the numerator.

$$\frac{1}{4^{-2}}=1\cdot\frac{4^{2}}{1}=\frac{16}{1}=16$$

16

In the follwoing video you will see examples of simplifying expressions with negative exponents.

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## Simplify expressions using a combination of exponent rules

Once the rules of exponents are understood, you can begin simplifying more complicated expressions. There are many applications and formulas that make use of exponents, and sometimes expressions can get pretty cluttered. Simplifying an expression before evaluating can often make the computation easier, as you will see in the following example which makes use of the quotient rule to simplify before substituting 4 for x.

### Example

Evaluate $$x=4$$.

[hidden-answer a=”389478″]Separate into numerical and variable factors.

$$\displaystyle \left( \frac{24}{2} \right)\left( \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[1]/p[3]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[1]/p[3]/span[2], line 1, column 3 \right)$$

Divide coefficients, and subtract the exponents of the variables.

$$\displaystyle 12\left( ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[1]/p[5]/span, line 1, column 2 \right)$$

Simplify.

$$\displaystyle 12 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[1]/p[7]/span, line 1, column 2$$

Substitute the value 4 for the variable x.

$$\displaystyle (12)( ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[1]/p[9]/span, line 1, column 2 )=12\cdot 64$$

$$\displaystyle \frac{24 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[1]/div/p[1]/span[1], line 1, column 2 }{2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[1]/div/p[1]/span[2], line 1, column 2 }$$ = 768

### Example

Evaluate $$x=4$$ and $$y=-2$$.

[hidden-answer a=”261413″]In the denominator, notice that a product is being raised to a power.

Use the rules of exponents to simplify the denominator.

$$\displaystyle{\left(2{x}^{3}y\right)}^{2}={2}^{2}{x}^{3\cdot 2}{y}^{2}={2}^{2}{x}^{6}{y}^{2}={4x^{6}y^{2}}$$

Here is the fraction with a simplified denominator:

$$\frac{24x^{8}y^{2}}{4x^{6}y^{2}}$$

Separate into numerical and variable factors to simplify further.

$$\displaystyle \left( \frac{24}{4} \right)\left( \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[8]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[8]/span[2], line 1, column 3 \right)\left( \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[8]/span[3], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[8]/span[4], line 1, column 3 \right)$$

Divide coefficients, use the Quotient Rule to divide the variables—subtract the exponents.

$$\displaystyle 6\left( ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[10]/span[1], line 1, column 2 \right)\left( ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[10]/span[2], line 1, column 2 \right)$$

Simplify. Remember that $$y^{0}$$ is 1.

$$\displaystyle 6 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[12]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[12]/span[2], line 1, column 2 =6 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[12]/span[3], line 1, column 2$$

Substitute the value 4 for the variable x.

$$\displaystyle (6)( ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[2]/p[14]/span, line 1, column 2 )=6\cdot 16$$

$$x=4$$ and $$y=-2$$

Notice that you could have worked this problem by substituting 4 for x and 2 for y in the original expression. You would still get the answer of 96, but the computation would be much more complex. Notice that you didn’t even need to use the value of y to evaluate the above expression.

In the following video you are shown examples of evaluating an exponential expression for given numbers.

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Usually, it is easier to simplify the expression before substituting any values for your variables, but you will get the same answer either way. In the next examples, you will see how to simplify expressions using different combinations of the rules for exponents.

### Example

Simplify. $$a^{2}\left(a^{5}\right)^{3}$$

[hidden-answer a=”526055″]Raise $$a^{5}$$ to the power of 3 by multiplying the exponents together (the Power Rule).

$$\displaystyle ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/p[3]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/p[3]/span[2], line 1, column 2$$

Since the exponents share the same base, a, they can be combined (the Product Rule).

$$\displaystyle ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/p[5]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/p[5]/span[2], line 1, column 2 \\ ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/p[5]/span[3], line 1, column 2$$

$$\displaystyle ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/div/p[1]/span[1], line 1, column 2 ParseError: "}" expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/div/p[1]/span[2], line 1, column 3 = ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[3]/div/p[1]/span[3], line 1, column 2$$

The following examples require the use of all the exponent rules we have learned so far. Remember that the product, power, and quotient rules apply when your terms have the same base.

### Example

Simplify. $$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[1]/span[1], line 1, column 3 {8 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[1]/span[2], line 1, column 2 }$$

[hidden-answer a=”43782″]Use the order of operations.

Parentheses, Exponents, Multiply/ Divide, Add/ Subtract

There is nothing inside parentheses or brackets that we can simplify further, so we will evaluate exponents first.

Use the Power Rule to simplify $$\left(a^{5}\right)^{3}$$.

$$\left(a^{5}\right)^{3}=a^{5\cdot{3}}=a^{15}$$

The expression now looks like this:

$$\displaystyle\frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[8]/span[1], line 1, column 3 {8 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[8]/span[2], line 1, column 2 }$$

Now we can multiply, using the Product Rule to simplify the numerator because the bases are the same.

$$\displaystyle ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[10]/span[1], line 1, column 2 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[10]/span[2], line 1, column 2 =a^{17}$$, and the expression looks like this:

$$\displaystyle\frac ParseError: "}" expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[11]/span[1], line 1, column 2 ParseError: "}" expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[11]/span[2], line 1, column 3$$

Now we can divide using the Quotient Rule.

$$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/p[13]/span, line 1, column 3 {8}$$

$$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/div/p[1]/span[1], line 1, column 3 {8 ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/div/p[1]/span[2], line 1, column 2 }=\frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[9]/div[4]/div/p[1]/span[3], line 1, column 3 {8}$$

## Simplify Expressions With Negative Exponents

Now we will add the last layer to our exponent simplifying skills and practice simplifying compound expressions that have negative exponents in them. It is standard convention to write exponents as positive because it is easier for the user to understand the value associated with positive exponents, rather than negative exponents.

Use the following summary of negative exponents to help you simplify expressions with negative exponents.

### Rules for Negative Exponents

With a, b, m, and n not equal to zero, and m and n as integers, the following rules apply:

$$a^{-m}=\frac{1}{a^{m}}$$

$$\frac{1}{a^{-m}}=a^{m}$$

$$\frac{a^{-n}}{b^{-m}}=\frac{b^m}{a^n}$$

When you are simplifying expressions that have many layers of exponents, it is often hard to know where to start. It is common to start in one of two ways:

• Rewrite negative exponents as positive exponents
• Apply the product rule to eliminate any “outer” layer exponents such as in the following term: $$\left(5y^3\right)^2$$

We will explore this idea with the following example:

Simplify. $$\displaystyle ParseError: invalid DekiScript (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[10]/p[5]/span[1], line 1, column 1 \cdot \,\, ParseError: invalid DekiScript (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[10]/p[5]/span[2], line 1, column 1$$

Write your answer with positive exponents. The table below shows how to simplify the same expression in two different ways, rewriting negative exponents as positive first, and applying the product rule for exponents first. You will see that there is a column for each method that describes the exponent rule or other steps taken to simplify the expression.

 Rewrite with positive Exponents First Description of Steps Taken Apply the Product Rule for Exponents First Description of Steps Taken $$ParseError: invalid DekiScript (click for details)Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[10]/table/tbody/tr/td[1]/span, line 1, column 1$$ to the denominator with a positive exponent $$\frac{\left(4^5x^{15}\right)}{\left(2^4x^{8}\right)}$$ Use the product rule to apply the outer exponents to the terms inside each set of parentheses. $$\left(\frac{4^5}{2^4}\right)\left(\frac{x^{15}}{x^{8}}\right)$$ Regroup the numerical terms and the variables to make combining like terms easier $$\left(\frac{4^5}{2^4}\right)\left(x^{15-8}\right)$$ Use the quotient rule to simplify the x terms $$\left(\frac{1,024}{16}\right)\left(x^{7}\right)$$ Expand the numerical terms $$64x^{7}$$ Divide the numerical terms $$64x^{7}$$ Divide the numerical terms

If you compare the two columns that describe the steps that were taken to simplify the expression, you will see that they are all nearly the same, except the order is changed slightly. Neither way is better or more correct than the other, it truly is a matter of preference.

Example

Simplify $$\frac{\left(t^{3}\right)^2}{\left(t^2\right)^{-8}}$$

We can either rewrite this expression with positive exponents first or use the Product Raised to a Power Rule first.

Let’s start by simplifying the numerator and denominator using the Product Raised to a Power Rule.

Numerator: $$\left(t^{3}\right)^2=t^{3\cdot{2}}=t^6$$

Denominator: $$\left(t^2\right)^{-8}=t^{2\cdot{-8}}=t^{-16}$$

Now the expression looks like this:

$$\frac{t^6}{t^{-16}}$$

We can use the quotient rule because we have the same base.

Quotient Rule: $$\frac{t^6}{t^{-16}}=t^{6-\left(-16\right)}=t^{6+16}=t^{22}$$

$$\frac{\left(t^{3}\right)^2}{\left(t^2\right)^{-8}}=t^{22}$$

Example

Simplify $$\frac{\left(5x\right)^{-2}y}{x^3y^{-1}}$$

This time, let’s start by rewriting the terms in the expression so they have positive exponents. The terms with negative exponents in the top will go to the bottom of the fraction, and the terms with negative exponents in the bottom will go to the top.

$$\begin{array}{c}\frac{\left(5x\right)^{-2}y}{x^3y^{-1}}\\\text{ }\\=\frac{\left({y^{1}}\right)y}{x^3\left(5x\right)^{2}}\end{array}$$

Note how we left the single y term in the top because it did not have a negative exponent on it, and we left the $$x^3$$ term in the bottom because it did not have a negative exponent on it.

Now we can apply the Product Raised to a Power Rule:

$$\frac{yy^{1}}{5^{2}x^3x^{2}}$$

Use the product rule to simplify further:

$$\frac{yy^{1}}{5^{2}x^3x^{2}}=\frac{y^2}{25x^{3+2}}=\frac{y^2}{25x^5}$$

We can’t simplify any further, so our answer is

$$\frac{\left(5x\right)^{-2}y}{x^3y^{-1}}=\frac{y^2}{25x^5}$$

In the next section, you will learn how to write very large and very small numbers using exponents. This practice is widely used in science and engineering.

## Summary

• Evaluating expressions containing exponents is the same as evaluating any expression. You substitute the value of the variable into the expression and simplify.
• The product rule for exponents: For any number x and any integers a and b, $$\left(x^{a}\right)\left(x^{b}\right) = x^{a+b}$$.
• The quotient rule for exponents: For any non-zero number x and any integers a and b: $$\displaystyle \frac ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[11]/ul/li[3]/span[1], line 1, column 3 ParseError: colon expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[11]/ul/li[3]/span[2], line 1, column 3 = ParseError: EOF expected (click for details) Callstack: at (Courses/Lumen_Learning/Beginning_Algebra_(Lumen)/04:_Exponents/4.03:_Rules_for_Exponents), /content/body/div[11]/ul/li[3]/span[3], line 1, column 2$$
• The power rule for exponents:
1. For any nonzero numbers a and b and any integer x, $$\displaystyle {\left(\frac{a}{b}\right)}^{x}=\frac{a^{x}}{b^{x}}$$

CC licensed content, Original

CC licensed content, Shared previously

• Unit 11: Exponents and Polynomials, from Developmental Math: An Open Program. Provided by: Monterey Institute of Technology and Education. Located at: nrocnetwork.org/resources/downloads/nroc-math-open-textbook-units-1-12-pdf-and-word-formats/. License: CC BY: Attribution
• Ex: Simplify Exponential Expressions Using the Power Property of Exponents. Authored by: James Sousa (Mathispower4u.com) for Lumen Learning. Located at: https://youtu.be/Hgu9HKDHTUA. License: CC BY: Attribution
• Ex: Simplify Fractions Raised to Powers (Positive Exponents Only) Version 1. Authored by: James Sousa (Mathispower4u.com) for Lumen Learning. Located at: https://youtu.be/ZbxgDRV35dE. License: CC BY: Attribution
• College Algebra. Authored by: Jay Abrams et, al.. Provided by: Lumen Learning. Located at: courses.candelalearning.com/collegealgebra1xmaster/. License: CC BY: Attribution
• Ex: Negative Exponents - Basics. Authored by: James Sousa (Mathispower4u.com) . Located at: https://youtu.be/WvFlHjlIITg. License: CC BY: Attribution

## FAQs

### What are the 5 rules of exponents? ›

Laws Of Exponents
• Powers with Same Base.
• Quotient with Same Base.
• Power of a Power.
• Product to a Power.
• Quotient to a Power.
• Zero Power Rule.
• Negative Exponent Rule.
• Fractional Exponent Rule.

What are the 7 rules for exponents laws of exponents? ›

Make sure you go over each exponent rule thoroughly in class, as each one plays an important role in solving exponent based equations.
• Product of powers rule. ...
• Quotient of powers rule. ...
• Power of a power rule. ...
• Power of a product rule. ...
• Power of a quotient rule. ...
• Zero power rule. ...
• Negative exponent rule.
Jun 14, 2021

What is a trick for exponents? ›

If you're multiplying exponents that have the same base, add the exponents together. So if you have x^2 times x^3, it becomes x^5. But if you're taking the exponent of a base that already has an exponent, you multiply those exponents together.

What are the rules of exponents for dummies? ›

Laws of Exponents. When multiplying like bases, keep the base the same and add the exponents. When raising a base with a power to another power, keep the base the same and multiply the exponents. When dividing like bases, keep the base the same and subtract the denominator exponent from the numerator exponent.

What are exponents 9th grade? ›

Remember that exponents are a shorthand way of writing repeated multiplication of the same number by itself. For example:5×5×5=53. The exponent, which is 3 in this example, stands for however many times the value is being multiplied. The number that is being multiplied, which is 5 in this example, is called the base.

What are the 4 laws of exponents? ›

Laws of Exponent at a Glance
Law of Reciprocalan=1/an
Power of Product Rule(a×b)n=an×bn
Quotient Law of Exponentsxm÷xn=xm-n
Power Law of Exponents(xm)n=xmn
Power of Quotient Rule(a/b)n=an/bn
2 more rows

What is the exponent rule with example? ›

When a number is raised to some power then the power on the base number is called Exponent. Exponent simply means a base number is multiplied by itself equal to the power mentioned on it. For Example, if we say Pn this means P is multiplied by itself 'n' a number of times.

What are 5 real life examples of exponents? ›

Exponents are used in Computer Game Physics, pH and Richter Measuring Scales, Science, Engineering, Economics, Accounting, Finance, and many other disciplines. Exponential Growth is a critically important aspect of Finance, Demographics, Biology, Economics, Resources, Electronics and many other areas.

What is the shortcut for finding exponent? ›

Select and hold the Alt key on the numeric keypad. Type the alt code (0185) in sequence for exponent one using the numeric keypad. Similarly, use Alt + 0178 for exponent two and Alt + 0179 for exponent three.

What is the first rule of rules of exponents? ›

First, any number raised to the power of "one" equals itself. This makes sense, because the power shows how many times the base is multiplied by itself. If it's only multiplied one time, then it's logical that it equals itself.

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