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Need help with exponents

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
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Need help with exponents

by mmcleod » Thu Apr 08, 2010 6:43 am
Does anyone know a good website that explains the different fundamentals of exponents. I have a basic understanding, but I definitely need to improve. Here are a couple of problems that I'm struggling with, so if anyone can provide a step-by-step solution, that would be great!

10^8 - 10^2
-----------------
10^7 - 10^4

The Answer = 10

also...

a^2 - b^2
--------------
b - a

The Answer = -a-b
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by papgust » Thu Apr 08, 2010 6:54 am
10^8 - 10^2 / 10^7 - 10^4

10^2 (10^6 - 1) / 10^4 (10^3 - 1)

10^6 - 1 = 10^6 (approx)
10^3 - 1 = 10^3 (approx)

10^2 * 10^6 / 10^4 * 10^3

10^8 / 10^7 = 10.



a^2 - b^2 / b-a
a^2 - b^2 = (a+b) (a-b)
(a+b) (a-b) / b-a

(a+b) (a-b) / -(a-b)

(a-b) gets cancelled,

(a+b) / -1

-(a+b)

-a-b
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