## Sunday, May 3, 2009

### B0B

Hey, here is my bob for the exponents and logarithms unit.

I was at the U of W for last week so I missed a lot of stuff, but after reading over the slides and doing the homework I think I have a grasp on what I'm doing.

Some things that I think will be important for the test are:

A logarithm is an exponent!

That means that when you are multiplying 2 logarithms (logMN) it is the same as adding them! (logM + logN) This is known as the product law.

When dividing 2 logarithms (logM/N) it is the same as subtracting them! (logM - logN) This is known as the quotient law.

When you have an exponent (logM^N) it is the same as multiplying (NlogM) This is known as the power law.

It would also be handy to remember the change of base law. This means that when you want to change the base of log all you have to do is divide log the base you have by log the base you want. (If that makes sense? It helps me to think of it that way)

Also know the equations for finding interest A= Pe^rt. (this also works for decaying questions or for finding the half life!)
A is the end amount. P is the amount you start with. r is the rate. t is the time in years.

This equation is handy for word problems, but if it doesn't work there is always A= P(1+r/n)^tn
where n is the number of times the principle is compunded per year.

ln is the natural logarithm, it is the same as log base e, but we never write this! Just write ln! We can use ln the exact same way we use log!

Well those are the things that I discovered from doing the homework. I think that pretty much sums up the unit.

I think the hardest part of this test will be remembering the word problems because I wasn't in class to learn what not to do. Hopefully my day of studying will pay off though because I feel like I really understand this unit! (: