SOLUTION: Solve the following equation for x: e2x + ex -12 =0

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Question 866936: Solve the following equation for x:
e2x + ex -12 =0
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Substitute, u=e%5Ex, then u%5E2=e%5E%282x%29
u%5E2%2Bu-12=0
%28u%2B4%29%28u-3%29=0
Two "u" solutions:
u%2B4=0
u=-4
e%5E%28x%29=-4
This is not a valid solution.
u-3=0
u=3
e%5Ex=3
x=ln%283%29