anonymous one year ago Find the volume using cylindrical shells y = 2ex, y = 2e−x, x = 1; about the y-axis

1. myininaya

2. myininaya

or did you mean y=2e^x,y=2e^(-x),x=1

3. anonymous

I meant the second one sorry

4. myininaya

|dw:1436215459219:dw|

5. myininaya

|dw:1436215629655:dw| so this is the part we want to rotate about the y-axis

6. myininaya

|dw:1436215740336:dw|

7. anonymous

ok

8. myininaya

so since everything is in terms of x you know the y=2e^x and the y=2e^(-x) we are looking at parallel strips to the axis of rotation (like we are already set it up we just have to plug into our formula ) |dw:1436215827622:dw|

9. myininaya

|dw:1436215907363:dw|

10. myininaya

are you cool? do you think you can enter into the formula?

11. myininaya

$\int\limits_{\text{ lower limit }}^{\text{ upper limit }}2 \pi (Radius)(height) dx$

12. myininaya

hint: the height I was trying to show in the picture is just the difference of those two functions

13. anonymous

yea thank you for the help. So would it have 2 radii

14. myininaya

radius is x because the distance the curve is from the axis of rotation is x