SOLUTION: 3^2x +3^x = 12

Algebra ->  Test  -> Lessons -> SOLUTION: 3^2x +3^x = 12      Log On


   



Question 860626: 3^2x +3^x = 12
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
3^2x +3^x = 12
---------
Sub u for 3^x
u%5E2+%2B+u+-+12+=+0
(u+4)*(u-3) = 0
u = -4 --> 3^x = -4 extraneous, ignore
------
u = 3 --> 3^x = 3
x = 1