Questions about the world of GMAT Math from other sources and general math related questions.
JeffreyB581
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Variable w/ exponents DS theory question

by JeffreyB581 Wed Feb 03, 2016 6:55 pm

Started thinking about this question and wanted to double check my thought process.

x^-2 = ?

Restated: (1/x)^2=?

Statement 1: x^-1 = 1/2
Sufficient: x^1=2, therefore x^2=4, therefore x^-2=1/4

Statement 2: x^2=4?
Sufficient: x can be both +/- 2, but this does not change the fact that x^-2=1/4

My question is this: If the original statement was x^-3=?
Statement 1 would still be valid but statement 2 would not because the odd exponent requires that you know the sign. The answer could be 1/8 or -1/8. Is my thinking correct here?
RonPurewal
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Re: Variable w/ exponents DS theory question

by RonPurewal Tue Feb 09, 2016 8:26 am

hi,
per the forum rules, please cite the original source of this problem. thank you.