Post 17

Ok, so last week we pretty much just reviewed for the upcoming exams. Mrs. Robinson gave us two practice APs, which I failed. They mostly went over things we learned recently like integrals. The first one was much much better than the second one, which is pretty pathetic considering the second one was calculator allowed. We were also given the take home portion of the exam. This portion is only twenty multiple choice questions and is also calculator allowed. The one we will take on exam did will include multiple choice and essay, both of which calculators will not be allowed. Today I was going through the take home portion and I realized I forgot a lot of things we did in the beginning of the year. I thought I knew how to do some problems, but my answers were coming out wrong.

Anyway, two weeks ago we learned how to find volume of a curve. This is done by rotating the curve about an axis or line to make it a solid object. We did this by using both disks and washers. Disks are used when there is only one equation and the object rotated turns out to be a solid. When there are two equations, washers are used since there will be a hole in the figure.

The formula for disks is:
pi S a-b [R(x)]^2 dx

This is basically a definite integral where you plug in the function you are given and square it. Many people forget to square it. This completley changes everything, so don't forget.

The formula for washers is:
pi S a-b top^2-bottom^2 dx

This is also a definite integral where you have to square the functions. I like these because they're very similar to area under a curve, and I also liked those. The only difference is to square both functions given and put a pi on the outside of the integral.

Most of the things we learned recently I'm fine with, but I came to realize I'm confused with a lot of old things. I get average value, average rate of change, and other various things with those words arranged in different ways. I never really caught onto average rate of change, and I still don't know what it is. I also get confused with linerizaton. When I look at the questions, I never know what to do with them. Can someone explain?