SOLUTION: Prove that {{{log(B,a^x) = x*log(B,a)}}}

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Question 189335: Prove that
log%28B%2Ca%5Ex%29+=+x%2Alog%28B%2Ca%29

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Prove that
log%28B%2Ca%5Ex%29+=+x%2Alog%28B%2Ca%29

Let M equal the left side

M+=+log%28B%2Ca%5Ex%29 

Let N equal the right side

N+=+x%2Alog%28B%2Ca%29

Take the first equation:

M+=+log%28B%2Ca%5Ex%29

By definition of logarithms,

B%5EM+=+a%5Ex

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Take the second equation:

N+=+x%2Alog%28B%2Ca%29

Divide both sides by x

+N%2Fx+=+log%28B%2Ca%29+

By definition of logarithms,

B%5E%28N%2Fx%29=a

Raise both sides to the x power

%28B%5E%28N%2Fx%29%29%5Ex=a%5Ex

B%5EN=a%5Ex

------------------

So we have the two equations:

B%5EM+=+a%5Ex
B%5EN=a%5Ex

Therefore

B%5EM=B%5EN since both equal to a%5Ex

Therefore if B is positive and not equal to 1. then

M=N

Therefore

log%28B%2Ca%5Ex%29+=+x%2Alog%28B%2Ca%29

Edwin