ziyuenlau wrote:Is 1/(a - b) < b - a ?
(1) a > b
(2) (a + b)(a - b) > 0
OA=A
Hi ziyuenlau,
Question: Is 1/(a - b) < b - a?
Looking at (a - b) and (b - a), one can intuit that one of them would be a positive number and the other would be a negative number; so the fate of the question depends on the signs a and b take.
Statement 1: a > b
=> (a - b) is positive and (b - a) is negative
Thus, 1/(a - b) is positive.
Or, 1/(a - b) > b - a. The answer is NO. Sufficient.
Statement 2: (a + b)(a - b) > 0
=> a^2 > b^2
=> |a| > |b|
If a and b both are positive, a > b, The answer is NO.
However, if a and b both are negative, a < b, The answer is Yes. Insufficient.
The correct answer:
A
Hope this helps!
Relevant book:
Manhattan Review GMAT Data Sufficiency Guide
-Jay
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