PSAT Math : How to divide exponents

Study concepts, example questions & explanations for PSAT Math

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Example Questions

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Example Question #1 : How To Divide Exponents

5/ 25 = 

Possible Answers:

25

5

10

50

54 / 5

Correct answer:

25

Explanation:

25 = 5 * 5 = 52. Then 54 / 25 = 54 / 52

Now we can subtract the exponents because the operation is division. 54 / 5= 54 – 2 = 52 = 25. The answer is therefore 25.

Example Question #121 : Exponents

Possible Answers:

Correct answer:

Explanation:

The key to this problem is understanding how exponents divide.  When two exponents have the same base, then the exponent on the bottom can simply be subtracted from the exponent on top.  I.e.:

Keeping this in mind, we simply break the problem down into prime factors, multiply out the exponents, and solve.

 

Example Question #1 : How To Divide Exponents

Simplify

\dpi{100} \small \frac{20x^{4}y^{-3}z^{2}}{5z^{-1}y^{2}x^{2}}=

Possible Answers:

\dpi{100} \small 15x^{2}y^{2}z^{2}

\dpi{100} \small \frac{4x^{2}z^{3}}{y^{5}}

\dpi{100} \small 15x^{-2}y^{-2}z^{-2}

\dpi{100} \small {4x^{5}y^{-2}}

None

Correct answer:

\dpi{100} \small \frac{4x^{2}z^{3}}{y^{5}}

Explanation:

Divide the coefficients and subtract the exponents.

Example Question #1 : How To Divide Exponents

Which of the following is equal to the expression Equationgre, where  

xyz ≠ 0?

Possible Answers:

z

1/y

xyz

xy

z/(xy)

Correct answer:

1/y

Explanation:

(xy)4 can be rewritten as x4y4 and z0 = 1 because a number to the zero power equals 1.  After simplifying, you get 1/y. 

Example Question #1 : How To Divide Exponents

If , then

 

Possible Answers:

Cannot be determined

Correct answer:

Explanation:

Start by simplifying the numerator and denominator separately. In the numerator, (c3)2 is equal to c6. In the denominator, c2 * c4 equals c6 as well. Dividing the numerator by the denominator, c6/c6, gives an answer of 1, because the numerator and the denominator are the equivalent.

 

Example Question #1 : How To Divide Exponents

If , which of the following is equal to ?

Possible Answers:

a

a6

The answer cannot be determined from the above information

a4

a18

Correct answer:

a18

Explanation:

The numerator is simplified to  (by adding the exponents), then cube the result. a24/a6 can then be simplified to .

Example Question #151 : Exponents

Possible Answers:

\dpi{100} \small 28

\dpi{100} \small 42

\dpi{100} \small 7

\dpi{100} \small 343

\dpi{100} \small 49

Correct answer:

\dpi{100} \small 7

Explanation:

The easiest way to solve this is to simplify the fraction as much as possible. We can do this by factoring out the greatest common factor of the numerator and the denominator. In this case, the GCF is 

Now, we can cancel out the  from the numerator and denominator and continue simplifying the expression.

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