Is x + y > 0 ?
(1) x - y > 0
(2) x^2 - y^2 > 0
[spoiler] Statement 2 I could easily answer by x^2 - y^2 => (x + y) (x - y).
So (x + y) ( x - y) > 0 which means either (x + y) is pos and (x - y) is pos, or (x + y) is neg AND (x - y) is neg. so insuff.
The original statement can be rephrased as "is x > -y?" and statement 1 can be rephrased as "x > y". But these 2 statements can't both be true so statement 1 is sufficient to answer the question. [/spoiler].
Am I right? Thanks.
(1) x - y > 0
(2) x^2 - y^2 > 0
[spoiler] Statement 2 I could easily answer by x^2 - y^2 => (x + y) (x - y).
So (x + y) ( x - y) > 0 which means either (x + y) is pos and (x - y) is pos, or (x + y) is neg AND (x - y) is neg. so insuff.
The original statement can be rephrased as "is x > -y?" and statement 1 can be rephrased as "x > y". But these 2 statements can't both be true so statement 1 is sufficient to answer the question. [/spoiler].
Am I right? Thanks.
