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By the end of this section, you will be able to:
  • Simplify expressions with exponents
  • Simplify expressions using the Product Property for Exponents
  • Simplify expressions using the Power Property for Exponents
  • Simplify expressions using the Product to a Power Property
  • Simplify expressions by applying several properties
  • Multiply monomials

Before you get started, take this readiness quiz.

  1. Simplify: 3 4 · 3 4 .
    If you missed this problem, review [link] .
  2. Simplify: ( −2 ) ( −2 ) ( −2 ) .
    If you missed this problem, review [link] .

Simplify expressions with exponents

Remember that an exponent indicates repeated multiplication of the same quantity. For example, 2 4 means to multiply 2 by itself 4 times, so 2 4 means 2 · 2 · 2 · 2 .

Let’s review the vocabulary for expressions with exponents.

Exponential notation

This figure has two columns. In the left column is a to the m power. The m is labeled in blue as an exponent. The a is labeled in red as the base. In the right column is the text “a to the m power means multiply m factors of a.” Below this is a to the m power equals a times a times a times a, followed by an ellipsis, with “m factors” written below in blue.

This is read a to the m t h power.

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

This figure has two columns. The left column contains 4 cubed. Below this is 4 times 4 times 4, with “3 factors” written below in blue. The right column contains negative 9 to the fifth power. Below this is negative 9 times negative 9 times negative 9 times negative 9 times negative 9, with “5 factors” written below in blue.

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

Simplify: 4 3 7 1 ( 5 6 ) 2 ( 0.63 ) 2 .

Solution


4 3 Multiply three factors of 4. 4 · 4 · 4 Simplify. 64


7 1 Multiply one factor of 7. 7


( 5 6 ) 2 Multiply two factors. ( 5 6 ) ( 5 6 ) Simplify. 25 36


( 0.63 ) 2 Multiply two factors. ( 0.63 ) ( 0.63 ) Simplify. 0.3969

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Simplify: 6 3 15 1 ( 3 7 ) 2 ( 0.43 ) 2 .

216 15 9 49 0.1849

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Simplify: 2 5 21 1 ( 2 5 ) 3 ( 0.218 ) 2 .

32 21 8 125 0.047524

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Simplify: ( −5 ) 4 5 4 .

Solution


  1. ( −5 ) 4 Multiply four factors of −5 . ( −5 ) ( −5 ) ( −5 ) ( −5 ) Simplify. 625


  2. 5 4 Multiply four factors of 5. ( 5 · 5 · 5 · 5 ) Simplify. −625
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Simplify: ( −3 ) 4 3 4 .

81 −81

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Simplify: ( −13 ) 2 13 2 .

169 −169

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Notice the similarities and differences in [link] and [link] ! Why are the answers different? As we follow the order of operations in part the parentheses tell us to raise the ( −5 ) to the 4 th power. In part we raise just the 5 to the 4 th power and then take the opposite.

Simplify expressions using the product property for 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.

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

x squared times x cubed.
What does this mean?
How many factors altogether?
x times x, multiplied by x times x. x times x has two factors. x times x times x has three factors. 2 plus 3 is five factors.
So, we have x to the fifth power.
Notice that 5 is the sum of the exponents, 2 and 3. x squared times x cubed is x to the power of 2 plus 3, or x to the fifth power.

We write:

x 2 · x 3 x 2 + 3 x 5

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

Product property for exponents

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

a m · a n = a m + n

To multiply with like bases, add the exponents.

An example with numbers helps to verify this property.

2 2 · 2 3 = ? 2 2 + 3 4 · 8 = ? 2 5 32 = 32

Simplify: y 5 · y 6 .

Solution

y to the fifth power times y to the sixth power.
Use the product property, a m · a n = a m+n . y to the power of 5 plus 6.
Simplify. y to the eleventh power.

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Simplify: b 9 · b 8 .

b 17

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Simplify: x 12 · x 4 .

x 16

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Simplify: 2 5 · 2 9 3 · 3 4 .

Solution


  1. 2 to the fifth power times 2 to the ninth power.
    Use the product property, a m · a n = a m+n . 2 to the power of 5 plus 9.
    Simplify. 2 to the 14th power.

  2. 3 to the fifth power times 3 to the fourth power.
    Use the product property, a m · a n = a m+n . 3 to the power of 5 plus 4.
    Simplify. 3 to the ninth power.
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Simplify: 5 · 5 5 4 9 · 4 9 .

5 6 4 18

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Simplify: 7 6 · 7 8 10 · 10 10 .

7 14 10 11

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Simplify: a 7 · a x 27 · x 13 .

Solution


  1. a to the seventh power times a.
    Rewrite, a = a 1 . a to the seventh power times a to the first power.
    Use the product property, a m · a n = a m+n . a to the power of 7 plus 1.
    Simplify. a to the eighth power.

  2. x to the twenty-seventh power times x to the thirteenth power.
    Notice, the bases are the same, so add the exponents. x to the power of 27 plus 13.
    Simplify. x to the fortieth power.
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Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
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2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
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can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
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Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
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A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
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Source:  OpenStax, Elementary algebra. OpenStax CNX. Jan 18, 2017 Download for free at http://cnx.org/content/col12116/1.2
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