GMAT Prep question

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GMAT Prep question

by SigGolfer » Wed Aug 22, 2007 8:29 am
I can't figure this one out for the life of me. Thanks a lot!

(1/5)^m x (1/4)^18 = 1 / (2 x (10^35))

The answer is m=35, but I don't understand how to get there.
Source: — Problem Solving |

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by erdnah » Wed Aug 22, 2007 8:48 am
(1/5)^m x (1/4)^18 = 1 / (2 x (10^35))
5^-m x 2^-36 = 2^-1 x 10^-35
5^-m x 2^-35 = 10^-35 (divide both sides by 2^-1)
5^-m = 5^-35 (divide both sides by 2^-35)
m = 35

come to the right answer, but i'm really not sure if my operations are correct; perhaps some exponent-specialists can help?!

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by beny » Wed Aug 22, 2007 10:32 am
(1/5)^m * (1/4)^18 = 1/(2*10^35)
5^m * 4^18 = 2 * 10^35
5^m * (2^2)^18 = 2 * 10^35
5^m * 2^36 = 2 * 10^35
5^m * 2^35 * 2 = 2 * 10^35
5^m * 2^35 = 10^35
m = 35