Question

Can someone have a look at the attached problem . I get the answer 112pi/15 but the document states its 64pi/15, and I can't see where I've gone wrong.
Graph:http://imgur.com/epnj7
Problem:http://imgur.com/tgGbq

Answer 1

I dont know the washer method, but there is another way of doing it , but getting the whole cylinder and subtracting the volume of the curve above the y axis.

Answer 2

i got the following integral

pi INT[( 2^2 - (2-(1/8)x^2)] between 4 an 0

Answer 3

ok'

Answer 4

wait I have had a little look at these before

Answer 5

I think you might have the integral wrong the wrong way

Answer 6

i 'm not familiar with washer method so i looked it up in a textbook!

Answer 7

oh - well i figured that the R referred to the radius of the cylinder or outer washer that is 2

Answer 8

inner radius is (2 -(1/8)x^2 ) , outer radius is 4

Answer 9

and the second part was the nonshaded area above the curve

Answer 10

exactly

Answer 11

I think you missed a square somewhere

Answer 12

\[= \pi \int\limits_{0}^{4} ( 2^2- ( 2- \frac{1}{8} x^2)^2 dx\]

Answer 13

yes - thats the integral i used

Answer 14

the previous one was a typo

Answer 15

now i calculated that as 112pi / 15