SOLUTION: 3^(2x)+3^x=20

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Question 107570: 3^(2x)+3^x=20
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let u=3%5Ex
3%5E%282x%29%2B3%5Ex=20
u%5E2%2Bu=20
u%5E2%2Bu-20=0
%28u%2B5%29%28u-4%29=0
u=-5 and u=4
Since u=3%5Ex, the negative solution is not possible.
u=4
3%5Ex=4
x=log%283%2C4%29
x=1.26186
Check your answer,
3%5E%282x%29%2B3%5Ex=20
3%5E%282%281.26186%29%29%2B3%5E%281.26186%29=20
16%2B4=20
20=20
True statement. Good solution.