If x and y are integers such that x^2= 2y and xy = 32, then x – y = ? Choose one.
A) - 30	B) - 20	C) - 5	D) - 4	E) 20

Rationale: "here x and y are integers . x ^ 2 = 2 y , xy = 32 . substitute ( x ^ 2 ) / 2 = y in xy = > x ^ 3 = 32 * 2 = > x ^ 3 = 64 . here x 3 is positive , x is also positive . x = 4 then y = 8 . x - y = - 4 so option d is correct"
Answer: D