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x 5 x 2 = x x x x x x x = ( x x ) x x x ( x x ) = x x x = x 3 . Notice that 5 2 = 3 .

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a 8 a 3 = a a a a a a a a a a a = ( a a a ) a a a a a ( a a a ) = a a a a a = a 5 . Notice that 8 3 = 5 .

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Quotient rule for exponents

If x is a real number and n and m are natural numbers,

x n x m = x n m , x 0 .

To divide two exponential quantities having the same nonzero base, subtract the exponent of the denominator from the exponent of the numerator. Keep in mind that the exponential quantities being divided must have the same base for this rule to apply.

Sample set c

Find the following quotients. All exponents are natural numbers.

x 5 x 2 = x 5-2 = x 3 The part in the box is usally done mentally .

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27 a 3 b 6 c 2 3 a 2 b c = 9 a 3 2 b 6 1 c 2 1 = 9 a b 5 c

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15 x 3 x = 5 x

The bases are the same, so we subtract the exponents. Although we don’t know exactly what is, the notation indicates the subtraction.

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Practice set c

Find each quotient

( x + 6 ) 5 ( x + 6 ) 3

( x + 6 ) 2

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26 x 4 y 6 z 2 13 x 2 y 2 z

2 x 2 y 4 z

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When we make the subtraction, n m , in the division x n x m , there are three possibilities for the values of the exponents:

  1. The exponent of the numerator is greater than the exponent of the denominator, that is, n > m . Thus, the exponent, n m , is a natural number.
  2. The exponents are the same, that is, n = m . Thus, the exponent, n m , is zero, a whole number.
  3. The exponent of the denominator is greater than the exponent of the numerator, that is, n < m . Thus, the exponent, n m , is an integer.

Zero as an exponent

In Sample Set C, the exponents of the numerators were greater than the exponents of the denominators. Let’s study the case when the exponents are the same.

When the exponents are the same, say n , the subtraction n n produces 0.

Thus, by the second rule of exponents, x n x n = x n n = x 0 .

But what real number, if any, does x 0 represent? Let’s think for a moment about our experience with division in arithmetic. We know that any nonzero number divided by itself is one.

8 8 = 1 , 43 43 = 1 , 258 258 = 1

Since the letter x represents some nonzero real number, so does x n . Thus, x n x n

represents some nonzero real number divided by itself. Then x n x n = 1 .

But we have also established that if x 0 , x n x n = x 0 . We now have that x n x n = x 0

and x n x n = 1 . This implies that x 0 = 1 , x 0 .

Exponents can now be natural numbers and zero. We have enlarged our collection of numbers that can be used as exponents from the collection of natural numbers to the collection of whole numbers.

Zero as an exponent

If x 0 , x 0 = 1

Any number, other than 0, raised to the power of 0, is 1. 0 0 has no meaning (it does not represent a number).

Sample set d

Find each value. Assume the base is not zero.

2 x 2 x 2 = 2 x 0 = 2 1 = 2

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5 ( x + 4 ) 8 ( x 1 ) 5 5 ( x + 4 ) 3 ( x 1 ) 5 = ( x + 4 ) 8 3 ( x 1 ) 5 5 = ( x + 4 ) 5 ( x 1 ) 0 = ( x + 4 ) 5

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Practice set d

Find each value. Assume the base is not zero.

6 x 4 2 x 3

3 x 4 3 = 3 x

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14 a 7 7 a 2

2 a 7 2 = 2 a 5

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26 x 2 y 5 4 x y 2

13 2 x y 3

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36 a 4 b 3 c 8 8 a b 3 c 6

9 2 a 3 c 2

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51 ( a 4 ) 3 17 ( a 4 )

3 ( a 4 ) 2

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52 a 7 b 3 ( a + b ) 8 26 a 2 b ( a + b ) 8

2 a 5 b 2

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14 x r y p z q 2 x r y h z 5

7 y p h z q 5

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We will study the case where the exponent of the denominator is greater than the exponent of the numerator in Section [link] .

Exercises

Use the product rule and quotient rule of exponents to simplify the following problems. Assume that all bases are nonzero and that all exponents are whole numbers.

12 x y 3 z 2 4 x 2 y 2 z 3 x

144 x 4 y 5 z 3

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( 4 x 2 ) ( 8 x y 3 )

32 x 3 y 3

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( 2 x y ) ( 3 y ) ( 4 x 2 y 5 )

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( 1 4 a 2 b 4 ) ( 1 2 b 4 )

1 8 a 2 b 8

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( 3 8 ) ( 16 21 x 2 y 3 ) ( x 3 y 2 )

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15 x 20 y 24 z 4 5 x 19 y z

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24 x 4 y 4 z 0 w 8 9 x y w 7

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a 4 b 6 ( a 10 b 16 a 5 b 7 )

a 9 b 15

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3 a 2 b 3 ( 14 a 2 b 5 2 b )

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( x + 3 y ) 11 ( 2 x 1 ) 4 ( x + 3 y ) 3 ( 2 x 1 )

( x + 3 y ) 8 ( 2 x 1 ) 3

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40 x 5 z 10 ( z x 4 ) 12 ( x + z ) 2 10 z 7 ( z x 4 ) 5

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x n x n + 3

x 2 n + 3

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a Δ a b b

a Δ + b +

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Exercises for review

( [link] ) What natural numbers can replace x so that the statement 5 < x 3 is true?

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( [link] ) Use the distributive property to expand 4 x ( 2 a + 3 b ) .

8 a x + 12 b x

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( [link] ) Express x x x y y y y ( a + b ) ( a + b ) using exponents.

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( [link] ) Find the value of 4 2 + 3 2 2 3 10 8 .

8

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( [link] ) Find the value of 4 2 + ( 3 + 2 ) 2 1 2 3 5 + 2 4 ( 3 2 2 3 ) 4 2 .

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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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cm
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A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
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Can you compute that for me. Ty
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Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
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chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
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A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
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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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you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
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?
Joseph Reply
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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progressive wave
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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. May 08, 2009 Download for free at http://cnx.org/content/col10614/1.3
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