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!
Inequality from MGMAT
This topic has expert replies
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
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