SOLUTION: This one is really stumping me... Havent got into the ln function yet, only using log base 10 at this point Solve the following exponential equation using logarithms: (3^2x)-(3

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: This one is really stumping me... Havent got into the ln function yet, only using log base 10 at this point Solve the following exponential equation using logarithms: (3^2x)-(3      Log On


   



Question 408961: This one is really stumping me... Havent got into the ln function yet, only using log base 10 at this point
Solve the following exponential equation using logarithms:
(3^2x)-(3^x)=216

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
(3^2x)-(3^x)=216
Sub w for 3^x
--> w^2 - w - 216 = 0
w = 1/2 + sqrt(865)/2 (the 2nd solution is negative, and can't be used)
Sub back
3^x = 1/2 ± sqrt(865)/2
3^x =~ 15.20544
x*log(3) = log(15.20544)
x = log(15.20544)/log(3)
x =~ 2.477
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