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What is y in terms of x?

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What is y in terms of x?

by mehravikas » Tue Sep 30, 2008 12:55 pm
If 5^x - 5^(x-3) = (124) 5^y, what is y in terms of x?

a. x
b. x - 6
c. x - 3
d. 2x + 3
e. 2x + 6

Answer is: c
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by anju » Tue Sep 30, 2008 12:58 pm
5^x - 5^(x-3)
= 5^(x-3) (5^3 - 1) - take out common values
= 5^(x-3) (125-1)
=124*5^(x-3) = 124*5^y

so y = x-3
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