HG10 wrote:Is 1/(x - y) < y - x ?
1. y is positive
2. x is negative
Answer: C
Statement 1: y is positive
No restrictions on x.
Thus, it is possible x-y=1 or that x-y = -1.
If x-y = 1, then y-x = -1.
Plugging these values into 1/(x-y) < y-x, we get:
1/1 < -1
1 < -1.
NO.
If x-y = -1, then y-x = 1.
Plugging these values into 1/(x-y) < y-x, we get:
1/-1 < 1
-1 < 1.
YES.
Since in the first case the answer is NO, and in the second case the answer is YES, INSUFFICIENT.
Statement 2: x is negative
No restrictions on y.
Thus, it is possible that x-y=1 or that x-y = -1.
As we saw above, if x-y=1, then the answer to the question stem is NO, but if x-y=-1, then the answer to the question stem is YES.
INSUFFICIENT.
Statements 1 and 2:
Since x<0 and y>0, x-y<0 and y-x>0.
Plugging these conditions into 1/(x-y) < y-x, we get:
1/negative < positive.
negative < positive.
SUFFICIENT.
The correct answer is
C.
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