Learning Objectives
By the end of this section, you will be able to:
- Simplify expressions using the Quotient Property of Exponents
- Simplify expressions with zero exponents
- Simplify expressions using the Quotient to a Power Property
- Simplify expressions by applying several properties
- Divide monomials
Be Prepared 10.9
Before you get started, take this readiness quiz.
Simplify: 824.
If you missed the problem, review Example 4.19.
Be Prepared 10.10
Simplify: (2m3)5.
If you missed the problem, review Example 10.23.
Be Prepared 10.11
Simplify: 12x12y.
If you missed the problem, review Example 4.23.
Simplify Expressions Using the Quotient Property of Exponents
Earlier in this chapter, we developed the properties of exponents for multiplication. We summarize these properties here.
Summary of Exponent Properties for Multiplication
If a,b are real numbers and m,n are whole numbers, then
Now we will look at the exponent properties for division. A quick memory refresher may help before we get started. In Fractions you learned that fractions may be simplified by dividing out common factors from the numerator and denominator using the Equivalent Fractions Property. This property will also help us work with algebraic fractions—which are also quotients.
Equivalent Fractions Property
If a,b,c are whole numbers where b≠0,c≠0, then
As before, we'll try to discover a property by looking at some examples.
Considerx5x2andx2x3What do they mean?x⋅x⋅x⋅x⋅xx⋅xx⋅xx⋅x⋅xUse the Equivalent Fractions Property.x⋅x⋅x⋅x⋅xx⋅x⋅1x⋅x⋅1x⋅x⋅xSimplify.x31x
Notice that in each case the bases were the same and we subtracted the exponents.
- When the larger exponent was in the numerator, we were left with factors in the numerator and 1 in the denominator, which we simplified.
- When the larger exponent was in the denominator, we were left with factors in the denominator, and 1 in the numerator, which could not be simplified.
We write:
Quotient Property of Exponents
If a is a real number, a≠0, and m,n are whole numbers, then
A couple of examples with numbers may help to verify this property.
When we work with numbers and the exponent is less than or equal to 3, we will apply the exponent. When the exponent is greater than 3, we leave the answer in exponential form.
Example 10.45
Simplify:
- ⓐ x10x8
- ⓑ 2922
Solution
To simplify an expression with a quotient, we need to first compare the exponents in the numerator and denominator.
ⓐ | |
Since 10 > 8, there are more factors of x in the numerator. | x10x8 |
Use the quotient property with m>n,aman=am−n. | |
Simplify. | x2 |
ⓑ | |
Since 9 > 2, there are more factors of 2 in the numerator. | 2922 |
Use the quotient property with m>n,aman=am−n. | |
Simplify. | 27 |
Notice that when the larger exponent is in the numerator, we are left with factors in the numerator.
Try It 10.89
Simplify:
- ⓐ x12x9
- ⓑ 71475
Try It 10.90
Simplify:
- ⓐ y23y17
- ⓑ 81587
Example 10.46
Simplify:
- ⓐ b10b15
- ⓑ 3335
Solution
To simplify an expression with a quotient, we need to first compare the exponents in the numerator and denominator.
ⓐ | |
Since 15 > 10, there are more factors of b in the denominator. | b10b15 |
Use the quotient property with n>m,aman=1an−m. | |
Simplify. | 1b5 |
ⓑ | |
Since 5 > 3, there are more factors of 3 in the denominator. | 3335 |
Use the quotient property with n>m,aman=1an−m. | |
Simplify. | 132 |
Apply the exponent. | 19 |
Notice that when the larger exponent is in the denominator, we are left with factors in the denominator and 1 in the numerator.
Try It 10.91
Simplify:
- ⓐ x8x15
- ⓑ 12111221
Try It 10.92
Simplify:
- ⓐ m17m26
- ⓑ 78714
Example 10.47
Simplify:
- ⓐ a5a9
- ⓑ x11x7
Solution
ⓐ | |
Since 9 > 5, there are more a's in the denominator and so we will end up with factors in the denominator. | a5a9 |
Use the Quotient Property for n>m,aman=1an−m. | |
Simplify. | 1a4 |
ⓑ | |
Notice there are more factors of x in the numerator, since 11 > 7. So we will end up with factors in the numerator. | x11x7 |
Use the Quotient Property for m>n,aman=an−m. | |
Simplify. | x4 |
Try It 10.93
Simplify:
- ⓐ b19b11
- ⓑ z5z11
Try It 10.94
Simplify:
- ⓐ p9p17
- ⓑ w13w9
Simplify Expressions with Zero Exponents
A special case of the Quotient Property is when the exponents of the numerator and denominator are equal, such as an expression like amam. From earlier work with fractions, we know that
In words, a number divided by itself is 1. So xx=1, for any x (x≠0), since any number divided by itself is 1.
The Quotient Property of Exponents shows us how to simplify aman when m>n and when n<m by subtracting exponents. What if m=n?
Now we will simplify amam in two ways to lead us to the definition of the zero exponent.
Consider first 88, which we know is 1.
88=1 | |
Write 8 as 23. | 2323=1 |
Subtract exponents. | 23−3=1 |
Simplify. | 20=1 |
We see aman simplifies to a a0 and to 1. So a0=1.
Zero Exponent
If a is a non-zero number, then a0=1.
Any nonzero number raised to the zero power is 1.
In this text, we assume any variable that we raise to the zero power is not zero.
Example 10.48
Simplify:
- ⓐ 120
- ⓑ y0
Solution
The definition says any non-zero number raised to the zero power is 1.
ⓐ | |
120 | |
Use the definition of the zero exponent. | 1 |
ⓑ | |
y0 | |
Use the definition of the zero exponent. | 1 |
Try It 10.95
Simplify:
- ⓐ 170
- ⓑ m0
Try It 10.96
Simplify:
- ⓐ k0
- ⓑ 290
Now that we have defined the zero exponent, we can expand all the Properties of Exponents to include whole number exponents.
What about raising an expression to the zero power? Let's look at (2x)0. We can use the product to a power rule to rewrite this expression.
(2x)0 | |
Use the Product to a Power Rule. | 20x0 |
Use the Zero Exponent Property. | 1⋅1 |
Simplify. | 1 |
This tells us that any non-zero expression raised to the zero power is one.
Example 10.49
Simplify: (7z)0.
Solution
(7z)0 | |
Use the definition of the zero exponent. | 1 |
Try It 10.97
Simplify: (−4y)0.
Try It 10.98
Simplify: (23x)0.
Example 10.50
Simplify:
- ⓐ (−3x2y)0
- ⓑ −3x2y0
Solution
ⓐ | |
The product is raised to the zero power. | (−3x2y)0 |
Use the definition of the zero exponent. | 1 |
ⓑ | |
Notice that only the variable y is being raised to the zero power. | −3x2y0 |
Use the definition of the zero exponent. | −3x2⋅1 |
Simplify. | −3x2 |
Try It 10.99
Simplify:
- ⓐ (7x2y)0
- ⓑ 7x2y0
Try It 10.100
Simplify:
- ⓐ −23x2y0
- ⓑ (−23x2y)0
Simplify Expressions Using the Quotient to a Power Property
Now we will look at an example that will lead us to the Quotient to a Power Property.
(xy)3 | |
This means | xy⋅xy⋅xy |
Multiply the fractions. | x⋅x⋅xy⋅y⋅y |
Write with exponents. | x3y3 |
Notice that the exponent applies to both the numerator and the denominator.
We see that (xy)3 is x3y3.
We write:(xy)3x3y3
This leads to the Quotient to a Power Property for Exponents.
Quotient to a Power Property of Exponents
If a and b are real numbers, b≠0, and m is a counting number, then
To raise a fraction to a power, raise the numerator and denominator to that power.
An example with numbers may help you understand this property:
Example 10.51
Simplify:
- ⓐ (58)2
- ⓑ (x3)4
- ⓒ (ym)3
Solution
ⓐ | |
Use the Quotient to a Power Property, (ab)m=ambm. | |
Simplify. |
ⓑ | |
Use the Quotient to a Power Property, (ab)m=ambm. | |
Simplify. |
ⓒ | |
Raise the numerator and denominator to the third power. |
Try It 10.101
Simplify:
- ⓐ (79)2
- ⓑ (y8)3
- ⓒ (pq)6
Try It 10.102
Simplify:
- ⓐ (18)2
- ⓑ (−5m)3
- ⓒ (rs)4
Simplify Expressions by Applying Several Properties
We'll now summarize all the properties of exponents so they are all together to refer to as we simplify expressions using several properties. Notice that they are now defined for whole number exponents.
Summary of Exponent Properties
If a,b are real numbers and m,n are whole numbers, then
Example 10.52
Simplify: (x2)3x5.
Solution
(x2)3x5 | |
Multiply the exponents in the numerator, using the Power Property. |
x6x5 |
Subtract the exponents. | x |
Try It 10.103
Simplify: (a4)5a9.
Try It 10.104
Simplify: (b5)6b11.
Example 10.53
Simplify: m8(m2)4.
Solution
m8(m2)4 | |
Multiply the exponents in the numerator, using the Power Property. |
m8m8 |
Subtract the exponents. | m0 |
Zero power property | 1 |
Try It 10.105
Simplify: k11(k3)3.
Try It 10.106
Simplify: d23(d4)6.
Example 10.54
Simplify: (x7x3)2.
Solution
(x7x3)2 | |
Remember parentheses come before exponents, and the bases are the same so we can simplify inside the parentheses. Subtract the exponents. |
(x7−3)2 |
Simplify. | (x4)2 |
Multiply the exponents. | x8 |
Try It 10.107
Simplify: (f14f8)2.
Try It 10.108
Simplify: (b6b11)2.
Example 10.55
Simplify: (p2q5)3.
Solution
Here we cannot simplify inside the parentheses first, since the bases are not the same.
(p2q5)3 | |
Raise the numerator and denominator to the third power using the Quotient to a Power Property, (ab)m=ambm |
(p2)3(q5)3 |
Use the Power Property, (am)n=am⋅n. | p6q15 |
Try It 10.109
Simplify: (m3n8)5.
Try It 10.110
Simplify: (t10u7)2.
Example 10.56
Simplify: (2x33y)4.
Solution
(2x33y)4 | |
Raise the numerator and denominator to the fourth power using the Quotient to a Power Property. |
(2x3)4(3y)4 |
Raise each factor to the fourth power, using the Power to a Power Property. |
24(x3)434y4 |
Use the Power Property and simplify. | 16x1281y4 |
Try It 10.111
Simplify: (5b9c3)2.
Try It 10.112
Simplify: (4p47q5)3.
Example 10.57
Simplify: (y2)3(y2)4(y5)4.
Solution
(y2)3(y2)4(y5)4 | |
Use the Power Property. | (y6)(y8)y20 |
Add the exponents in the numerator, using the Product Property. | y14y20 |
Use the Quotient Property. | 1y6 |
Try It 10.113
Simplify: (y4)4(y3)5(y7)6.
Try It 10.114
Simplify: (3x4)2(x3)4(x5)3.
Divide Monomials
We have now seen all the properties of exponents. We'll use them to divide monomials. Later, you'll use them to divide polynomials.
Example 10.58
Find the quotient: 56x5÷7x2.
Solution
56x5÷7x2 | |
Rewrite as a fraction. | 56x57x2 |
Use fraction multiplication to separate the number part from the variable part. |
567⋅x5x2 |
Use the Quotient Property. | 8x3 |
Try It 10.115
Find the quotient: 63x8÷9x4.
Try It 10.116
Find the quotient: 96y11÷6y8.
When we divide monomials with more than one variable, we write one fraction for each variable.
Example 10.59
Find the quotient: 42x2y3−7xy5.
Solution
42x2y3−7xy5 | |
Use fraction multiplication. | 42−7⋅x2x⋅y3y5 |
Simplify and use the Quotient Property. | −6⋅x⋅1y2 |
Multiply. | −6xy2 |
Try It 10.117
Find the quotient: −84x8y37x10y2.
Try It 10.118
Find the quotient: −72a4b5−8a9b5.
Example 10.60
Find the quotient: 24a5b348ab4.
Solution
24a5b348ab4 | |
Use fraction multiplication. | 2448⋅a5a⋅b3b4 |
Simplify and use the Quotient Property. | 12⋅a4⋅1b |
Multiply. | a42b |
Try It 10.119
Find the quotient: 16a7b624ab8.
Try It 10.120
Find the quotient: 27p4q7−45p12q.
Once you become familiar with the process and have practiced it step by step several times, you may be able to simplify a fraction in one step.
Example 10.61
Find the quotient: 14x7y1221x11y6.
Solution
14x7y1221x11y6 | |
Simplify and use the Quotient Property. | 2y63x4 |
Be very careful to simplify 1421 by dividing out a common factor, and to simplify the variables by subtracting their exponents.
Try It 10.121
Find the quotient: 28x5y1449x9y12.
Try It 10.122
Find the quotient: 30m5n1148m10n14.
In all examples so far, there was no work to do in the numerator or denominator before simplifying the fraction. In the next example, we'll first find the product of two monomials in the numerator before we simplify the fraction.
Example 10.62
Find the quotient: (3x3y2)(10x2y3)6x4y5.
Solution
Remember, the fraction bar is a grouping symbol. We will simplify the numerator first.
(3x3y2)(10x2y3)6x4y5 | |
Simplify the numerator. | 30x5y56x4y5 |
Simplify, using the Quotient Rule. | 5x |
Try It 10.123
Find the quotient: (3x4y5)(8x2y5)12x5y8.
Try It 10.124
Find the quotient: (−6a6b9)(−8a5b8)−12a10b12.
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Section 10.4 Exercises
Practice Makes Perfect
Simplify Expressions Using the Quotient Property of Exponents
In the following exercises, simplify.
31234
u9u3
y4y
x10x30
r2r8
225
Simplify Expressions with Zero Exponents
In the following exercises, simplify.
100
x0
−40
- ⓐ (3a)0
- ⓑ 3a0
- ⓐ (−92y8z)0
- ⓑ −92y8z0
- ⓐ −60
- ⓑ −61
8·m0−4·n0
Simplify Expressions Using the Quotient to a Power Property
In the following exercises, simplify.
(45)3
(p2)5
(ab)8
(2xy)4
Simplify Expressions by Applying Several Properties
In the following exercises, simplify.
(y4)3y7
(y2)5y6
p11(p5)3
a3·a4a7
(uu10)2
(x3·x8x4)3
(z6)2(z2)4
(x4)8(x5)7
(3m24n)3
(15z4·z90.3z2)0
(p4)2(p3)5(p2)9
(−2y3)4(3y4)2(−6y3)2
Divide Monomials
In the following exercises, divide the monomials.
42a14÷6a2
20u8÷(−4u6)
36y94y7
18x5−27x9
24p7q6p2q5
10a4b50a2b6
48x11y9z336x6y8z5
(10u2v)(4u3v6)5u9v2
(6a4b3)(4ab5)(12a8b)(a3b)
Mixed Practice
- ⓐ 24a5+2a5
- ⓑ 24a5−2a5
- ⓒ 24a5⋅2a5
- ⓓ 24a5÷2a5
- ⓐ p4⋅p6
- ⓑ (p4)6
- ⓐ y3y
- ⓑ yy3
(8x5)(9x)÷6x3
27a73a3+54a99a5
32y58y2−60y105y7
63r6s39r4s2−72r2s26s
Everyday Math
Memory One megabyte is approximately 106 bytes. One gigabyte is approximately 109 bytes. How many megabytes are in one gigabyte?
Memory One megabyte is approximately 106 bytes. One terabyte is approximately 1012 bytes. How many megabytes are in one terabyte?
Writing Exercises
Vic thinks the quotient x20x4 simplifies to x5. What is wrong with his reasoning?
When Dimple simplified −30 and (−3)0 she got the same answer. Explain how using the Order of Operations correctly gives different answers.
Self Check
ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.
ⓑ On a scale of 1–10, how would you rate your mastery of this section in light of your responses on the checklist? How can you improve this?