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21 Dec 2015, 09:15
Kudos
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D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
84% (01:02) correct
16%
(01:14)
wrong
based on 399
sessions
History
Date
Time
Result
Not Attempted Yet
If \(x≠0\), is \(-\frac{4}{x^3}\) negative?
(1) \(x\) is positive.
(2) \(x^3 - x^2\) is positive.
(1) \(x\) is positive.
(2) \(x^3 - x^2\) is positive.
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
21 Dec 2015, 09:25
Kudos
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If \(x≠0\), is \(-\frac{4}{x^3}\) negative?
Notice that the question basically asks whether x is a positive number, because if it is then \(-\frac{4}{x^3} =-(\frac{positive}{positive})=negative\).
(1) \(x\) is positive. Directly answers the question. Sufficient.
(2) \(x^3 - x^2\) is positive --> x^3- x^2 > 0 --> x^3 > x^2 --> reduce by x^2 (we can safely do that because x^2 will be positive): x > 1. The same here: x is positive. Sufficient.
Answer: D.
Hope it's clear.
Notice that the question basically asks whether x is a positive number, because if it is then \(-\frac{4}{x^3} =-(\frac{positive}{positive})=negative\).
(1) \(x\) is positive. Directly answers the question. Sufficient.
(2) \(x^3 - x^2\) is positive --> x^3- x^2 > 0 --> x^3 > x^2 --> reduce by x^2 (we can safely do that because x^2 will be positive): x > 1. The same here: x is positive. Sufficient.
Answer: D.
Hope it's clear.
21 Dec 2015, 09:31
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Bunuel
Thanks. You got KUDO, as my token of appreciation.
