posted by jess .
Solve x = log3 15
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