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Confused on this problem on roots.

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
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Confused on this problem on roots.

by w0283767 » Sun Aug 22, 2010 4:11 pm
The size of a square computer screen is measured by the length of its diagonal. How much bigger is the visible area of a square 24 inch screen than the area of a 20 inch screen?

I know the formula to solve or s =d / √s

I haven't done roots in a while and am having a hard time visualizing what is going on mathematically here.

How does (24 / √2) simplify to 12√2?

I know they are equal, but am not understanding.

Thank you in advance for your time.
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by w0283767 » Sun Aug 22, 2010 5:49 pm
Figured it out myself.

FYI:

To simplify 24 / √2 = (24 / √2) * (√2 / √2) = (24√2) / (√2 *√2) = 24√2 / √4 = 24√2 / 2 = 12/√2.

That is a rule I haven't used in a long time.
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by Tani » Mon Aug 23, 2010 8:19 am
First, the formula is the diagonal of a square divided by the square root of 2 = the side, not hte square root of s. Check out your 45/45/90 triangle.
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by w0283767 » Mon Aug 23, 2010 2:52 pm
That was a typo. Thanks.
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by Tani » Mon Aug 23, 2010 4:44 pm
Aha! Typos are my specialty! :-)
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