gmat1220 wrote:

Guys

The answer sounds unconvincing. Can you verify this?

Does x = y ?

(1) x^2 - y^2 = 0

(2) (x + y)^2 = 0

Try to solve it using substitution and it will get clearer:

Q: Does x=y?

Two cases;

Case I: x != y; x=-1, y=1

Case II: x = y; x=0, y=0

(1) x^2=y^2

Case I satisfies.

Case II satisfies.

So, we have two sets both satisfying this statement. However, in one case x=y and in other x!=y. We can't conclude that x=y.

(1) x=-y

Case I satisfies.

Case II satisfies.

So, we have two sets both satisfying this statement. However, in one case x=y and in other x!=y. We can't conclude that x=y.

Combining;

The same two cases satisfy. Nothing conclusive.

Ans: "E"

If the questions said:

"Does x=y if xy!=0". Then "B" would be the answer.

_________________

~fluke

GMAT Club Premium Membership - big benefits and savings