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Official Guide Explanation:Problem Solving #144

Background

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Review (12th 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: 144
Page: 172
Difficulty: 5 (Moderate)
Category 1: Algebra > Solving Quadratic Equations > other
Category 2: Algebra > Linear Equations-One Unk >

Explanation: Work with the first equation to come up with a value of x or something that might apply to the equation you're looking to solve:

((4 - x)/(2 + x)) = x

4 - x = 2x + x2

4 = x2 + 3x

x2 + 3x - 4 = 0, choice (C). It looked like there'd be more steps than this, but the GMAT rarely requires you to go through more than a half - dozen or so steps. Watch for shortcuts like this one!

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