(Untitled)

[abdicate_it]

So I was away from my intro calc course for three classes because of tonsilitis

Comments

[korean_guy_01]

a*log(b) = log(ba)

log(a)-log(b) = log(a/b)

log(a)+log(b) = log(a*b)

log(u) = a -> 10a = u

log() & ln() can be interchanged for each line, but you have to swap all of them

[quantumfoam13]

and for the last one, when you change to ln, you should swap the 10 with e.

[korean_guy_01]

yep

[abdicate_it]

So are all tens...slash multiples of tens swapped with e's?

[where_was_i]

I have a suspicion that all the definitions above look similar to the ones in your textbook. When you try to think about them again this may help: Logarithms turn multiplication into addition. It's kind of a simple statement, and may seem unclear at first but you'll see that all the definitions follow directly from that principle. (And isn't it easier to remember one basic premise than the ten definitions that follow from it?) For example: having 4log2's is the same as log2 + log2 + log2 + log2 (you add the logs) or log(2x2x2x2), where it's sort of like you 'factor out' the log, and by doing so convert all the plus signs into multiplication signs. Play around with it, and you'll hopefully see how everything falls into place.

[abdicate_it]

So addition and multiplication and subtraction and division?

I can never work from textbook definitions either, so if I missed something I'm just screwed. All I got from it was the inversion I think. And even that was hazy.

Thank you so much, explaining it super simplified helps. Thats why I don't like the textbook, I don't get why people need to overphrase and complicate things when they can be said so easily.

[where_was_i]

The same concept indeed holds for subtraction of logs: the numbers inside the logs are divided instead of multiplied when you subtract.