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Source: Official Guide for GMAT Review 2016 Problem Solving; #206




2 Explanations


Yannaphol Kaewbaidhoon

key step here is the difference fo squares (a^2 - b^2) = (a-b)(a+b)

Sep 4, 2017 • Comment

Sam Kinsman

Yes, that's right! :)

Sep 12, 2017 • Reply


Gravatar Mike McGarry, Magoosh Tutor

Aug 17, 2015 • Comment

Mumin Khan

This problem is just sadistic.

Oct 12, 2017 • Reply

Jonathan , Magoosh Tutor

It's not easy! :) But it's important to know your FOIL identities COLD, including (a^2 - b^2) = (a + b)(a - b)

Nov 6, 2017 • Reply

Roger Kille


Jul 30, 2018 • Reply

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Section 5.3 Problem Solving

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