SOLUTION: 9^u-7*3^u+12=0

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Question 958717: 9^u-7*3^u+12=0
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
9^u-7*3^u+12=0
3^2u-7*3^u+12=0
let 3^u=a
3^2u=a^2
a^2-7a+12=0
(a-4)(a-3)=0
..
a=4=3^u
take log of both sides
log4=ulog3
u=log4/log3=1.2619
or
a=3=3^u
take log of both sides
log3=ulog3
u=log3/log3=1