SOLUTION: What is the value of U in the equation; log{{{9}}}(3u+14) - log{{{9}}}5 = log{{{9}}}2u? I tried to work it myself and got an answer of -9, but I don't think it's right because ther

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Question 20541: What is the value of U in the equation; log(3u+14) - log5 = log2u? I tried to work it myself and got an answer of -9, but I don't think it's right because there was a similar problem in my book but they didn't show you how to do it. Can you please walk me through it?
Answer by AnlytcPhil(1806)   (Show Source): You can put this solution on YOUR website!


log9(3u+14) - log95 = log9(2u)

Add log95 to both sides

log9(3u+14) = log9(2u) + log95 

On the right use the rule of logarithms:

logBX + logBY = logB(XY)

logB(3u+14) = logB[(2u)×5]

logB(3u+14) = logB(10u)

Now we raise both sides to the 9 power, which amounts to

dropping the log9 on each side:

3u+14 = 10u

Solve that for u and get u=2.

Edwin

AnlytcPhil@aol.com







 













 

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