Inequality from MGMAT

[jo777]

Is x + y > 0?

(1) x – y > 0

(2) x^2 – y^2 > 0

Can anyone lend a hand? I see that a negative Y (larger than x) could make (1) possible or a larger X (assuming both sides are the same). So we need to know the signs of X/Y

I run into trouble with (2), however - how does this rule tell us the X and Y have to be the same sign. If I assume X is 3 and y is -2 and I factor: (x+y)(x-y), it seems that the answer is positive 5. I don't see how (2) proves that x and y have to have the same signs. Please help!

[Suyog]

IMO C.

I)
Take x = 5 and y = 3
x - y > 0 and x + y > 0

Take X = 5 and y = -7
x - y > 0 but x + y < 0
Insuff

II)
Take x = 5 and y = 3
x^2 - y^2 > 0 and x + y > 0

Take x = -5 and y = -3
x^2 - y^2 > 0 but x + y < 0

but if (I) & (II) both are true then x has to be greater than y and both shud be positive So it shud be C.

Wots the OA.

as far as ur doubt...
(x-y)^2 = (x+y)(x-y),
not x^2 - y^2

[bomond]

Agree with Suyog

other way for both statment is true.

x^2-y^2>0

(x-y)(x+y)>0

From ST 1 (x-y)>0 => +

Then in order to be (x-y)(x+y)>0
( +)(+) >0 x+y also must be +
Hence both are SUFF.