SOLUTION: Solve for x: (log2(x))^2-2log(x)-15=0

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Question 842695: Solve for x:
(log2(x))^2-2log(x)-15=0
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use a substitution, u=log%282%2Cx%29,
u%5E2-2u-15=0
%28u-5%29%28u%2B3%29=0
Two possible solutions:
u-5=0
u=5
log%282%2Cx%29=5
x=2%5E5=32
and
u%2B3=0
u=-3
log%282%2Cx%29=-3
x=2%5E%28-3%29=1%2F8