Posted by **jess** on Tuesday, June 12, 2012 at 1:52pm.

Solve x = log3 15

- math equations -
**Steve**, Tuesday, June 12, 2012 at 2:20pm
huh? there's nothing to solve. Just evaluate log3 15.

Now, you probably don't have a log-base-3 key on your calculator, so you have to use what you do have: ln

x = ln15/ln3

How does that work? By definition,

3^log3 15 = 15

ln(3^log3 15) = ln15

now, ln(3^p) = p*ln3, so we have

log3 15 * ln3 = ln15

log3 15 = ln15/ln3

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