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alex.gellatly
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(1) xy > 0 implies either both x and y are both positive or both are negative.alex.gellatly wrote:Data Sufficiency:
Is x > 0?
1) xy > 0
2) x + y > 0
Thanks in advanced
If x = 2, y = 3, then xy = 6 > 0. Here x > 0.
If x = -2, y = -3, then xy = 6 > 0. Here x < 0.
No definite answer; NOT sufficient.
(2) x + y > 0
If x = 3, y = 4, then x + y = 7 > 0. Here x > 0.
If x = -3, y = 5, then x + y = 2 > 0. Here x > 0.
No definite answer; NOT sufficient.
Combining (1) and (2), xy > 0 and x + y > 0.
If both x and y are negative, then x + y < 0, which means x cannot be negative. So, x has to be positive or x > 0; SUFFICIENT.
The correct answer is C.
