GMAT Practice Question: If x=a^6, y=b^6, b is not equal to 0, and a=4b, then...
Question
If x=a^6, y=b^6, b is not equal to 0, and a=4b, then x/y=
- 4
- 8
- 16
- 32
- 64
Topics: exponents, roots
Solution
Step 1
We first convert each cube root to fractional exponents using "Roots as Fractional Exponents" and simplify the exponents
x = a^6 1/3 = a^2 y = b^6 1/3 = b^2
Step 2
We form the ratio and rewrite it as a power of a fraction using "Exponents of Fractions"
x/y = a^2/b^2 (a/b)^2
Step 3
We substitute "a = 4 b" into the expression and calculate the square
(a/b)^2 = (4 b/b)^2 = 4^2 4^2 = 16
Answer
C
