Official Guide Explanation:
Problem Solving #144




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.

Click here for an example of the PDF booklets. Click here to purchase a PDF copy.


Solution and Metadata

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!

Click here for the full list of GMAT OG12 explanations.


You should follow me on Twitter. While you're at it, take a moment to subscribe to GMAT Hacks via RSS or Email.

Total GMAT Math

The comprehensive guide to the GMAT Quant section. It's "far and away the best study material available," including over 300 realistic practice questions and more than 500 exercises!
Click to read more.