GMATPrep square root invoving variables. Help!

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Hi,
Simply couldn't figure out how to go about cracking this problem. Someone please help!


Thanks.
Shilotilo
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by Canman » Tue Jul 22, 2008 5:43 am
First it helps to simplify the roots

Change 1/Sqrt(x+y) to:

Sqrt(x+y)/(x+y)

This should make the answer easier to understand.

1) Doesn't have to be bigger. What if x and y are the same number? Then it would be equal.

2) Must be bigger because the sum of the individual sqrts is larger than the sqrt of the sum. Plug a few numbers in to try it out.

3) Must be smaller for the same reason above.

Hope this helps.