M7MBA wrote:Does (x + a)^2 = y^2?
(1) x = y - a
(2) x = y + a
The OA is A .
Experts, what happen if a=0? Then both statements are suffcient. So, how should I think on this DS question?
Statement 1: x = y - a
Add 'a' to both sides to get x + a = y
Square both sides to get (x + a)^2 = y^2. So the answer is a definitive yes, S1 alone is sufficient.
Statement 2: Case 1: x = 1, y = 1, and a = 0. (1+0)^2 = 1^2, we have a YES to the initial question.
Case 2: x = 2, y = 1, and a = 1. (2 +1)^2 is not equal to 1^2, so we have a NO to the initial question.
S2 alone is not sufficient.
The answer is
A
(Notice that when a = 0, we're merely generating a YES to the initial question. Because a can assume other values that will generate a NO in statement 2, this statement is not sufficient.)
