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# Squaring Sides

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Intern
Joined: 24 Sep 2008
Posts: 9

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13 Oct 2008, 12:50
Could someone explain this for me? An answer in the 11th edition of the guide gives this answer for part of the diagnostic test:

square root of 3-2x=square root of 2x +1 (the +1 is not under brackets of the square root)

So it says to square both sides:

(square root of 3-2x)^2=(square root of 2x +1)^2

Then it has this:

3-2x=2x+2(square root of 2x)+1

I am not seeing how they got the terms for the side on the right. It looks like there is an addition +2 and a term that wasn't squared.

Could someone please explain this? If anyone has the 11th edition guide, the answer explanation is on page 53, upper left hand corner of the page.

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VP
Joined: 17 Jun 2008
Posts: 1474

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13 Oct 2008, 13:06
If the right side is sqrt(2x) + 1 then after squaring it, you will get what is mentioned.
Intern
Joined: 24 Sep 2008
Posts: 9

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13 Oct 2008, 13:15
Would you be able to show how that is done? I'm just not seeing it. I understand on the left side of the equation because the root sign is over all the equation.

Would someone be able to break this down for me?
Intern
Joined: 17 May 2007
Posts: 33

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13 Oct 2008, 21:50
Use FOIL, just like any other quantities being multiplied together:

[sqrt(2x) + 1] [sqrt(2x) + 1] =

sqrt(2x) * sqrt(2x) + sqrt(2x) + sqrt(2x) + 1 =

2x + 2*sqrt(2x) + 1

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This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: Squaring Sides &nbs [#permalink] 13 Oct 2008, 21:50
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# Squaring Sides

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