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10.2: Use Multiplication Properties of Exponents (Part 1)

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Learning Objectives
  • Simplify expressions with exponents
  • Simplify expressions using the Product Property of Exponents
  • Simplify expressions using the Power Property of Exponents
  • Simplify expressions using the Product to a Power Property
  • Simplify expressions by applying several properties
  • Multiply monomials
be prepared!

Before you get started, take this readiness quiz.

  1. Simplify: 3434. If you missed the problem, review Example 4.3.7.
  2. Simplify: (−2)(−2)(−2). If you missed the problem, review Example 3.7.6.

Simplify Expressions with Exponents

Remember that an exponent indicates repeated multiplication of the same quantity. For example, 24 means to multiply four factors of 2, so 24 means 2 • 2 • 2 • 2. This format is known as exponential notation.

Definition: Exponential Notation

On the left side, a raised to the m is shown. The m is labeled in blue as an exponent. The a is labeled in red as the base. On the right, it says a to the m means multiply m factors of a. Below this, it says a to the m equals a times a times a times a, with m factors written below in blue.

This is read a to the mth power.

In the expression am, the exponent tells us how many times we use the base a as a factor.

On the left side, 7 to the 3rd power is shown. Below is 7 times 7 times 7, with 3 factors written below. On the right side, parentheses negative 8 to the 5th power is shown. Below is negative 8 times negative 8 times negative 8 times negative 8 times negative 8, with 5 factors written below.

Before we begin working with variable expressions containing exponents, let’s simplify a few expressions involving only numbers.

Example 10.2.1:

Simplify: (a) 53 (b) 91

Solution

(a) 53

Multiply 3 factors of 5. 5 • 5 • 5
Simplify. 125

(b) 91

Multiply 1 factor of 9. 9
Exercise 10.2.1:

Simplify: (a) 43 (b) 111

Answer a

64

Answer b

11

Exercise 10.2.2:

Simplify: (a) 34 (b) 211

Answer a

81

Answer b

21

Example 10.2.2:

Simplify: (a) (78)2 (b) (0.74)2

Solution

(a) (78)2

Multiply two factors. (78)(78)
Simplify. 4964

(b) (0.74)2

Multiply two factors. (0.74)(0.74)
Simplify. 0.5476
Exercise 10.2.3:

Simplify: (a) (58)2 (b) (0.67)2

Answer a

2564

Answer b

0.4489

Exercise 10.2.4:

Simplify: (a) (25)3 (b) (0.127)2

Answer a

8125

Answer b

0.016129

Example 10.2.3:

Simplify: (a) (−3)4 (b) −34

Solution

(a) (−3)4

Multiply four factors of −3. (−3)(−3)(−3)(−3)
Simplify. 81

(b) −34

Multiply two factors. −(3 • 3 • 3 • 3)
Simplify. −81

Notice the similarities and differences in parts (a) and (b). Why are the answers different? In part (a) the parentheses tell us to raise the (−3) to the 4th power. In part (b) we raise only the 3 to the 4th power and then find the opposite.

Exercise 10.2.5:

Simplify: (a) (−2)4 (b) −24

Answer a

16

Answer b

-16

Exercise 10.2.6:

Simplify: (a) (−8)2 (b) −82

Answer a

64

Answer b

-64

Simplify Expressions Using the Product Property of Exponents

You have seen that when you combine like terms by adding and subtracting, you need to have the same base with the same exponent. But when you multiply and divide, the exponents may be different, and sometimes the bases may be different, too. We’ll derive the properties of exponents by looking for patterns in several examples. All the exponent properties hold true for any real numbers, but right now we will only use whole number exponents.

First, we will look at an example that leads to the Product Property.

  x2x2
What does this mean? How many factors altogether? CNX_BMath_Figure_10_02_015_img-02.png
So, we have x5
Notice that 5 is the sum of the exponents, 2 and 3. x2x3isx2+3,orx5
We write: x2x3x2+3x5

The base stayed the same and we added the exponents. This leads to the Product Property for Exponents.

Definition: Product Property of Exponents

If a is a real number and m, n are counting numbers, then

aman=am+n

To multiply with like bases, add the exponents.

An example with numbers helps to verify this property.

2223?=22+348?=2532=32

Example 10.2.4:

Simplify: x5 • x7.

Solution

Use the product property, am • an = am + n. x5+7
Simplify. x12
Exercise 10.2.7:

Simplify: x7 • x8.

Answer

x15

Exercise 10.2.8:

Simplify: x5 • x11.

Answer

x16

Example 10.2.5:

Simplify: b4 • b.

Solution

Rewrite, b = b1. b4b1
Use the product property, am • an = am + n. b4+1
Simplify. b5
Exercise 10.2.9:

Simplify: p9 • p.

Answer

p10

Exercise 10.2.10:

Simplify: m • m7.

Answer

m8

Example 10.2.6:

Simplify: 27 • 29.

Solution

Use the product property, am • an = am + n. 27+9
Simplify. 216
Exercise 10.2.11:

Simplify: 6 • 69.

Answer

610

Exercise 10.2.12:

Simplify: 96 • 99.

Answer

915

Example 10.2.7:

Simplify: y17 • y23.

Solution

Notice, the bases are the same, so add the exponents. y17+23
Simplify. y40
Exercise 10.2.13:

Simplify: y24 • y19.

Answer

y43

Exercise 10.2.14:

Simplify: z15 • z24.

Answer

z39

We can extend the Product Property of Exponents to more than two factors.

Example 10.2.8:

Simplify: x3 • x4 • x2.

Solution

Add the exponents, since the bases are the same. x3+4+2
Simplify. x9
Exercise 10.2.15:

Simplify: x7 • x5 • x9.

Answer

x21

Exercise 10.2.16:

Simplify: y3 • y8 • y4.

Answer

y15

Simplify Expressions Using the Power Property of Exponents

Now let’s look at an exponential expression that contains a power raised to a power. See if you can discover a general property.

  (x2)3
What does this mean? x2x2x2
How many factors altogether? CNX_BMath_Figure_10_02_021_img-03.png
So, we have x6
Notice that 6 is the product of the exponents, 2 and 3. (x2)3isx23orx6
We write: (x2)3x23x6

We multiplied the exponents. This leads to the Power Property for Exponents.

Definition: Power Property of Exponents

If a is a real number and m, n are whole numbers, then

(am)n=amn

To raise a power to a power, multiply the exponents.

An example with numbers helps to verify this property.

(52)3?=523(25)3?=5615,625=15,625

Example 10.2.9:

Simplify: (a) (x5)7 (b) (36)8

Solution

(a) (x5)7

Use the Power Property, (am)n = am • n. x57
Simplify. x35

(b) (36)8

Use the Power Property, (am)n = am • n. 368
Simplify. x48
Exercise 10.2.17:

Simplify: (a) (x7)4 (b) (74)8

Answer a

x28

Answer b

732

Exercise 10.2.18:

Simplify: (a) (x6)9 (b) (86)7

Answer a

y54

Answer b

842

Contributors and Attributions


This page titled 10.2: Use Multiplication Properties of Exponents (Part 1) is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by OpenStax.

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