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roots GMAC

by ddo » Sun Sep 14, 2008 8:21 am
Please see attached file.

Could sombody explain me why (√(9-√80))(√(9+√80)) = 1?

Thanks!
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by vishubn » Sun Sep 14, 2008 8:47 am
U sure OA is 1???

i get 20 as the answer ...
and i found out that is indeed the answer please find the solution here

https://www.beatthegmat.com/square-root- ... 16615.html

Vishu
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by ddo » Sun Sep 14, 2008 10:53 am
Hi Vishu,

Sorry, I realize the way I asked was not clear..

I got the 18 on the first part of the ecuation, but I couldnt convert the 2(....)(....) into 2. Right answer is 20.

Thks!
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by crisro » Sun Jul 10, 2011 11:09 am
why (√(9-√80))(√(9+√80)) = 1?

(√(9-√80))(√(9+√80)) = √(9-√80)(9+√80) = √(9^2-(√80)^2) = √(81-80) = √1 = 1
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