PSAT Math : How to subtract exponents

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : How To Subtract Exponents

If m and n are integers such that m < n < 0 and m2 – n2 = 7, which of the following can be the value of m + n?

            I. –5

           II. –7

          III. –9

Possible Answers:

I and II only

I only

II and III only

I, II and III only

II only

Correct answer:

II only

Explanation:

m and n are both less than zero and thus negative integers, giving us m2 and n2 as perfect squares. The only perfect squares with a difference of 7 is 16 – 9, therefore m = –4 and n = –3.

Example Question #16 : Exponential Operations

Possible Answers:

Correct answer:

Explanation:

To simplify, we can rewrite the numerator using a common exponential base.

Now, we can factor out the numerator.

The eights cancel to give us our final answer.

 

Example Question #17 : Exponential Operations

If , then what is ?

Possible Answers:

Correct answer:

Explanation:

Follow the order of operations by solving the expression within the parentheses first.

Return to solve the original expression.

 

Example Question #18 : Exponential Operations

Solve:

Possible Answers:

Correct answer:

Explanation:

 

Subtract the denominator exponent from the numerator's exponent, since they have the same base.

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