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# 6.2: Quotient Rules for Exponents

Difficulty Level: Advanced Created by: CK-12
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Practice Exponential Properties Involving Quotients
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Estimated11 minsto complete
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Suppose you have the expression:

xxxxxxxxxyyyyyxxxxxxyyy\begin{align*}\frac{x\cdot x \cdot x \cdot x \cdot x \cdot x \cdot x \cdot x \cdot x \cdot y \cdot y \cdot y \cdot y \cdot y}{x\cdot x \cdot x \cdot x \cdot x \cdot x \cdot y \cdot y \cdot y}\end{align*}

How could you write this expression in a more concise way?

### Watch This

James Sousa: Simplify Exponential Expressions- Quotient Rule

### Guidance

In the expression x3\begin{align*}x^3\end{align*}, the x\begin{align*}x\end{align*} is called the base and the 3\begin{align*}3\end{align*} is called the exponent. Exponents are often referred to as powers. When an exponent is a positive whole number, it tells you how many times to multiply the base by itself. For example:

• x3=xxx\begin{align*}x^3=x\cdot x \cdot x\end{align*}
• 24=2222=16\begin{align*}2^4=2\cdot 2 \cdot 2 \cdot 2=16\end{align*}.

There are many rules that have to do with exponents (often called the Laws of Exponents) that are helpful to know so that you can work with expressions and equations that involve exponents more easily. Here you will learn two rules that have to do with exponents and quotients.

RULE: To divide two powers with the same base, subtract the exponents.

m factorsaman=(a×a××a)(a×a××a) m>n;a0 n factorsaman=(a×a××a) mn factorsaman=amn

RULE: To raise a quotient to a power, raise both the numerator and the denominator to the power.

(ab)n=ab×ab××ab n factorsn factors (ab)n=(a×a××a)(b×b××b) n factors(ab)n=anbn (b0)

#### Example A

Simplify 27÷23\begin{align*}2^7 \div 2^3\end{align*}.

Solution:

27÷2327324The base is 2.Keep the base of 2 and subtract the exponents.The answer is in exponential form.

The answer can be taken one step further. The base is numerical so the term can be evaluated.

24=2×2×2×224=1627÷23=24=16

#### Example B

Simplify x8x2\begin{align*}\frac{x^8}{x^2}\end{align*}.

Solution:

x8x2x82x6x8x2=x6The base is x.Keep the base of x and subtract the exponents.The answer is in exponential form.

#### Example C

Simplify 16x5y54x2y3\begin{align*}\frac{16x^5 y^5}{4x^2 y^3}\end{align*}.

Solution:

16x5y54x2y34(x5y5x2y3)4x52y534x3y2The bases are x and y.Divide the coefficients - 16÷4=4. Keep the base of x and y andsubtract the exponents of the same base.

#### Concept Problem Revisited

xxxxxxxxxyyyyyxxxxxxyyy\begin{align*}\frac{x\cdot x \cdot x \cdot x \cdot x \cdot x \cdot x \cdot x \cdot x \cdot y \cdot y \cdot y \cdot y \cdot y}{x\cdot x \cdot x \cdot x \cdot x \cdot x \cdot y \cdot y \cdot y}\end{align*} can be rewritten as x9y5x6y3\begin{align*}\frac{x^9y^5}{x^6y^3}\end{align*} and then simplified to x3y2\begin{align*}x^3y^2\end{align*}.

### Vocabulary

Base
In an algebraic expression, the base is the variable, number, product or quotient, to which the exponent refers. Some examples are: In the expression 25\begin{align*}2^5\end{align*}, ‘2’ is the base. In the expression (3y)4\begin{align*}(-3y)^4\end{align*}, ‘3y\begin{align*}-3y\end{align*}’ is the base.
Exponent
In an algebraic expression, the exponent is the number to the upper right of the base that tells how many times to multiply the base times itself. Some examples are:
In the expression 25\begin{align*}2^5\end{align*}, ‘5’ is the exponent. It means to multiply 2 times itself 5 times as shown here: 25=2×2×2×2×2\begin{align*}2^5=2 \times 2 \times 2 \times 2 \times 2\end{align*}.
In the expression (3y)4\begin{align*}(-3y)^4\end{align*}, ‘4’ is the exponent. It means to multiply 3y\begin{align*}-3y\end{align*} times itself 4 times as shown here: (3y)4=3y×3y×3y×3y\begin{align*}(-3y)^4=-3y \times -3y \times -3y \times -3y\end{align*}.
Laws of Exponents
The laws of exponents are the algebra rules and formulas that tell us the operation to perform on the exponents when dealing with exponential expressions.

### Guided Practice

Simplify each of the following expressions.

1. (23)2\begin{align*}\left(\frac{2}{3}\right)^2\end{align*}

2. (x6)3\begin{align*}\left(\frac{x}{6}\right)^3\end{align*}

3. (3x4y)2\begin{align*}\left(\frac{3x}{4y}\right)^2\end{align*}

1. (23)2=2232=49\begin{align*}\left(\frac{2}{3}\right)^2=\frac{2^2}{3^2}=\frac{4}{9}\end{align*}

2. (x6)3=x363=x3216\begin{align*}\left(\frac{x}{6}\right)^3=\frac{x^3}{6^3}=\frac{x^3}{216}\end{align*}

3. (3x4y)2=32x242y2=9x216y2\begin{align*}\left(\frac{3x}{4y}\right)^2=\frac{3^2x^2}{4^2y^2}=\frac{9x^2}{16y^2}\end{align*}

### Practice

Simplify each of the following expressions, if possible.

1. (25)6\begin{align*}\left(\frac{2}{5}\right)^6\end{align*}
2. (47)3\begin{align*}\left(\frac{4}{7}\right)^3\end{align*}
3. (xy)4\begin{align*}\left(\frac{x}{y}\right)^4\end{align*}
4. 20x4y55x2y4\begin{align*}\frac{20x^4y^5}{5x^2y^4}\end{align*}
5. 42x2y8z26xy4z\begin{align*}\frac{42x^2y^8z^2}{6xy^4z}\end{align*}
6. (3x4y)3\begin{align*}\left(\frac{3x}{4y}\right)^3\end{align*}
7. 72x2y48x2y3\begin{align*}\frac{72x^2y^4}{8x^2y^3}\end{align*}
8. (x4)5\begin{align*}\left(\frac{x}{4}\right)^5\end{align*}
9. 24x14y83x5y7\begin{align*}\frac{24x^{14}y^8}{3x^5y^7}\end{align*}
10. 72x3y924xy6\begin{align*}\frac{72x^3y^9}{24xy^6}\end{align*}
11. (7y)3\begin{align*}\left(\frac{7}{y}\right)^3\end{align*}
12. 20x125x8\begin{align*}\frac{20x^{12}}{-5x^8}\end{align*}
1. Simplify using the laws of exponents: 2325\begin{align*}\frac{2^3}{2^5}\end{align*}
2. Evaluate the numerator and denominator separately and then simplify the fraction: 2325\begin{align*}\frac{2^3}{2^5}\end{align*}
3. Use your result from the previous problem to determine the value of a\begin{align*}a\end{align*}: 2325=12a\begin{align*}\frac{2^3}{2^5}=\frac{1}{2^{a}}\end{align*}
4. Use your results from the previous three problems to help you evaluate 24\begin{align*}2^{-4}\end{align*}.

### Answers for Explore More Problems

To view the Explore More answers, open this PDF file and look for section 6.2.

### Vocabulary Language: English

Base

Base

When a value is raised to a power, the value is referred to as the base, and the power is called the exponent. In the expression $32^4$, 32 is the base, and 4 is the exponent.
Exponent

Exponent

Exponents are used to describe the number of times that a term is multiplied by itself.
Power

Power

The "power" refers to the value of the exponent. For example, $3^4$ is "three to the fourth power".

## Date Created:

Apr 30, 2013

Feb 26, 2015
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