ab > a/b?
ab - a/b > 0
ab²/b - a/b > 0
(ab² - a) / b > 0
[ (a)(b² - 1) ] / b > 0
(a/b)(b² - 1) > 0?
Question stem, rephrased: Are a/b and b² - 1 the SAME SIGN?
Statement 1: |b| > 1
Thus, b² - 1 > 0.
No information about a/b.
INSUFFICIENT.
Statement 2: ab + a/b > 0
ab²/b + a/b > 0
(ab² + a) / b > 0
[ (a)(b² + 1) ] / b > 0
(a/b)(b² + 1) > 0.
Since it is not possible for b² + 1 to be negative, the inequality above holds true only if a/b > 0.
No information about b² - 1.
INSUFFICIENT.
Statements combined:
Statement 1: b² - 1 > 0.
Statement 2: a/b > 0.
Thus, a/b and b² - 1 are the SAME SIGN.
SUFFICIENT.
The correct answer is
C.
Last edited by
GMATGuruNY on Fri Aug 08, 2014 6:15 am, edited 1 time in total.
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