### Mr K, I have a question....(^_^)

I'm just wondering about logarithm problems like 2^x = 3^(2x+5),

*(long*

*answer 1.a on the pre-test)*and the answer is x = (5ln3)/(ln2 - 2ln3). My question is,

**when should I use the "ln" instead of "log**"? I mean, if I

**solved**that problem using

**common log**and got x = (5log3)/(log2- 2log3), am I

**wrong?**I have no problem on dealing with exponents and logarithms (i hope so, for my sake), just the use of "ln" and "log" confuses me. Im thinking to ask this question tomorrow, but maybe you don't have time tomorrow to answer questions.

## 2 Comments:

An excellent question!!

The answer is: it doesn't matter.

log (a) means log (base 10) of a

ln (a) means log (base

e) of aYou could even use log (base 7) of a, but that base isn't programmed into our calculators so it would be a little harder to do (you would have to use the "change of base" formula). That's why we tend to use log (a) or ln (a). I generally like to use ln (a) ONLY because it's one less letter to write. ;-)

I hope this clears it up for everyone. If not, post about it again. ;-)

thanks mr K. (^_^) now i can do the other hand outs too. from now on, i'll stick to "ln", and gotta review the stuff about compound interest too.

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