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May 18, 2013

# Homework Help: geometry

Posted by mattie on Sunday, July 11, 2010 at 11:49pm.

solve the equation 3^2x + 2.3^x - 15 = 0

• geometry - Reiny, Monday, July 12, 2010 at 6:43am

did you mean ...

3^(2x) + 2(3^x) - 15 = 0 ?

I will assume you did.

let 3^x = t
t^2 + 2t - 15 = 0
(t+5)(t-3) = 0
t = -5 or t = 3

then 3^x = -5, which has no solution or
3^x = 3
x = 1

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