GMAT Practice Question: If n is a positive integer, then (-2^n)^-2+(2^-n)^2=
Question
If n is a positive integer, then (-2^n)^-2+(2^-n)^2=
- 0
- 2^-2 n
- 2^2 n
- 2^-2 n+1
- 2^2 n+1
Topics: exponents, factoring, fractions
Solution
Step 1
We simplify the first term by separating the factor -1 and applying the rule for multiplying negative numbers an even number of times.
(-2^n)^-2 = (-1)^-2 2^-2n = 1 2^-2n = 2^-2n
Step 2
We simplify the second term by applying the power-of-a-power rule to the exponent.
(2^-n)^2 = 2^-2n
Step 3
We add the two identical simplified terms to find the final expression.
2^-2n + 2^-2n = 2 2^-2n = 2^-2n + 1
Answer
2^-2n + 1
