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## Official Guide Explanation:Data Sufficiency #81

Background

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Quantitative Review (2nd ed.). Click the links on the question number, difficulty level, and categories to find explanations for other problems.

These are the same explanations that are featured in my "Guides to the Official Guide" PDF booklets. However, because of the limitations of HTML and cross-browser compatibility, some mathematical concepts, such as fractions and roots, do not display as clearly online.

Question: 81
Page: 158
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Powers and Roots of Numbers >
Category 2: Algebra > Exponents >

Explanation: x2 is greater than x for any value of x that is not between 0 and 1. (For a more detailed explanation of that, see the explanation for question \#73, above.)

Statement (1) is sufficient: if x2 is greater than 1, x cannot be between 0 and 1, so x2 must be greater than x. Statement (2) is not sufficient: x could be between 0 and 1 (in which case x is greater than x2) or it could be less than 0 or greater than 1 (in which case x2 is greater than x). Choice (A) is correct.

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