If x < y, which of the following must be true?

[BTGmoderatorDC]

If x < y, which of the following must be true?

(A) x < y^2
(B) x^2 < y
(C) x^2 < y^2
(D) (x – y)^2 > 0
(E) x^3 > y



OA D

Source: Manhattan Prep

[Brent@GMATPrepNow]

If x < y, which of the following must be true?

(A) x < y^2
(B) x^2 < y
(C) x^2 < y^2
(D) (x – y)^2 > 0
(E) x^3 > y

If x < y, then we can also conclude that x ≠ y.
If x ≠ y, then we can be certain that x - y ≠ 0
If x - y ≠ 0, then we can be certain that (x – y)^2 > 0

Answer: D

ASIDE: Another approach would be to take values that satisfy the inequality x < y, and plug them into each answer choice until we eventually eliminate all answer choices other than D.
I'll leave that to you...