GMAT Arithmetic: If xy = 1, what is the value…
Question
If xy = 1, what is the value of (2^((x+y)^2))/(2^((x-y)^2))?
- 2
- 4
- 8
- 16
- 32
Topics: development formulas, calculations
Solution
Step 1
We apply exponent subtraction to combine the powers of two.
(2^((x+y)^2))/(2^((x-y)^2)) = 2^((x+y)^2-(x-y)^2)
Step 2
We apply "Development Formulas - Squares of +/-" to expand each squared binomial.
(x+y)^2 = x^2 + y^2 + 2xy (x-y)^2 = x^2 + y^2 - 2xy
Step 3
We subtract the expanded exponents to simplify the exponent expression.
(x+y)^2 - (x-y)^2 = 4xy
Step 4
We substitute the given value into the exponent and evaluate the power of two.
2^(4xy) = 2^(4×1) = 2^4 = 16
Answer
16 (D)
