Need Help Solving Q. 16 Diag Sec In 12th ed Official Guide

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acrowson: Junior | Next Rank: 30 Posts; Posts: 15; Joined: Mon Dec 28, 2009 10:36 am

by acrowson » Mon Jan 04, 2010 7:48 pm

*Please refer to the answer solution in the OG (sets the context for my question)*

Specifically, I need help understanding why both sides of the equation in the second step expand differently from each other?!
In other words, how the heck do we deal with (Root 2X + 1)*^2?

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Source: Beat The GMAT — Quantitative Reasoning | Mon Jan 04, 2010 7:48 pm

papgust: Community Manager; Posts: 1537; Joined: Mon Aug 10, 2009 6:10 pmFollowed by: 252 members; Thanked: 653 times

by papgust » Tue Jan 05, 2010 2:09 am

It is just a simple formula, (a+b)^2 = a^2 + b^2 + 2ab

[root(2x)+1]^2 = (root(2x))^2 + 1^2 + 2*root(2x)*1

And from here, it gets simplified.

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