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factor this out

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factor this out

by semidevil » Tue Mar 24, 2009 8:33 pm
5^k - 5^(k-1)

how do I factor this to become:
5^k - (1/5)5^k
(1-(1/5))5^k)
(4/5)5^k.

Is there some number properties Im missing?

this is from Eric's flashcards.
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by moadhia » Tue Mar 24, 2009 8:37 pm
5^(k-1) is equal to 5^K * 5^-1

to make it clearer, 2^-1 = 1/2 or 0.5

therefore, 5^(K-1) = 5^K * 5^-1 = (1/5)(5^K)

Its pretty straightfwd after that
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Re: factor this out

by Ossa » Wed Mar 25, 2009 5:03 am
Just remember that the key to this is: x^(a-b)=(x^a)/(x^b).
semidevil wrote:5^k - 5^(k-1)

how do I factor this to become:
5^k - (1/5)5^k
(1-(1/5))5^k)
(4/5)5^k.

Is there some number properties Im missing?

this is from Eric's flashcards.
Ossa Elhadary, PhD, CISA, PMP
Math Specialist
Test Prep New York
maximize your score, minimize your stress

www.testprepny.com
[email protected]
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