Question

Need help with the washer method:
x=1-y^2, x=2+y^2, =-1, y=1

Answer 1

*should be y=-1

Answer 2

x=-1 , y=-1?

Answer 3

try out this website. http://tutorial.math.lamar.edu/Classes/CalcII/CalcII.aspx

Answer 4

So you have two function. Find out which one is to the right.

Answer 5

x=2+y^2 would be to the right, right?

Answer 6

hold on

Answer 7

are your functions correct, they don't seem to intersect

Answer 8

yep, they are correct. I also forgot to put its revolved around the y-axis

Answer 9

because the functions don't even touch each other

Answer 10

That's really strange, I wonder if the text made an error

Answer 11

For washer method, we are supposed to take revolution of intersection between two functions

Answer 12

That much I understand, maybe I should try converting the equation to xs and see what happens.

Answer 13

If we change second function to
x=-2+y^2
we can solve it, do you wanna

Answer 14

sure : )

Answer 15

We will rotate around x=-3

Answer 16

Here come the integral

\[\pi \int\limits_{?}^{?}((-y^2-1)-(y^2-2)+1)^2-1\]

Answer 17

dy

Answer 18

did you get it, mathrocks?

Answer 19

Ok, this is starting to make some sense.

Answer 20

you have to find points of intersection though

Answer 21

Never memorize any formula for disc,shell, washer method

Answer 22

I can find the intersection points with no problem. It's just setting up the washer equation that sometimes trips me up. Thanks for your help, I appreciate it.

Answer 23

just know that when you are doing this type of problem, you are adding up circle

Answer 24

If I helped you in somehow, can you fan me

Answer 25

I'll remember that and will practice drawing the actual graphs.

And the fan request has been done. : )