GMAT Question of the Day - Data Sufficiency - Exponents
If 2^x = y^24 what is the value of x - y?
(1) x = 48
(2) x and y are both multiples of 2
GMAT Question of the Day Solution
Whenever you see even exponents consider that a negative value could be hidden. In this case you can see that because of the even exponent y^24 will be positive even if y is negative. For Statement (1) if x is 48 y must be 4 or -4. Two values of y yield two values for x - y so this statement is insufficient. Statement 2 tells us that both x and y are integers but we can use the same values from statement (1) and get multiple outcomes for x - y. Insufficient. Putting both statements together there is no new information.