## anonymous one year ago Which of the following statements is true? The volume of the solid formed by rotating the region bounded by the graph of y = x2, x = 3, y = 0 around the x-axis is https://gyazo.com/d4c15f518e12e0ca068dbf232b0c7b69

1. jim_thompson5910

do you have the graph set up?

2. anonymous

|dw:1444444321553:dw|

3. jim_thompson5910

this is what your graph should look like

4. anonymous

Oops, sorry Just a bit tired.

5. jim_thompson5910

the region in blue is going to be revolved around the x axis

6. anonymous

By looking at the graph, I'm going to have to say it's B

7. jim_thompson5910

|dw:1444446589968:dw|

8. jim_thompson5910

|dw:1444446606361:dw|

9. anonymous

If I'm following you correctly, 9.

10. jim_thompson5910

the vertical distance from the curve to the x axis

11. jim_thompson5910

it's going to be something with x in it

12. anonymous

Nope, completely lost here. |dw:1444446815097:dw| You're asking for that right?

13. jim_thompson5910

yes that length in terms of x (imagine it sliding back and forth between x = 0 and x = 3)

14. anonymous

Well it would change depending on what x is in the function y=x^2

15. jim_thompson5910

it's simply x^2, right?

16. jim_thompson5910

whatever x is, the vertical distance from the curve to the x axis is x^2 units

17. anonymous

jim pls why would you ask for the obvious? I am very tired ;(

18. anonymous

ok

19. anonymous

So how would I used that?

20. jim_thompson5910

|dw:1444447162670:dw|

21. jim_thompson5910

this 3D figure is made up of disks that look like this |dw:1444447207593:dw|

22. jim_thompson5910

imagine cutting it up into infinitely many disks that are infinitesimally small then glue those pieces together to form this 3D shape this is effectively what you are doing when you evaluate $\Large \pi\int_{a}^{b}(R)^2dx$ $\Large \pi\int_{0}^{3}(x^2)^2dx$ $\Large \pi\int_{0}^{3}(x^4)dx$

23. anonymous

nope, did not get it

24. anonymous

I'll look over it tomorrow when I'll be well rested.

25. jim_thompson5910

hmm strange how the system says it's wrong

26. jim_thompson5910

could be a typo somewhere

27. anonymous

What system?

28. jim_thompson5910

aren't you saying it's wrong?

29. jim_thompson5910

or the computer is telling you it's wrong?

30. anonymous

I was saying, I did not personally understand it very well.

31. jim_thompson5910

oh ok

32. anonymous

You are right. ;)