00:01
Okay, first we want to draw a picture.
00:03
So, y equals x cubed, goes through 0 ,0, 11, 2 ,8, and then also minus 1 ,1.
00:14
All right, so it looks like that.
00:17
That's this one.
00:20
And y equals x is the line at 45 degrees.
00:24
It also goes through 0 ,0, 0 ,0, and minus 1, 1.
00:36
Okay, so we're going to send that around the x -axis.
00:39
So i'm guessing that they mean both pieces of it.
00:49
Okay, so we're going to send both pieces around.
00:51
But we can do it by just sending the one in the first quadrant around and then multiplying it by two because the one in the third quadrant will give exactly the same thing.
01:01
Okay, don't spend any time drawing the three -dimensional thing because you don't really care what it looks like.
01:09
Okay, but if you did, it's, it's going to look like a cone on the outside.
01:16
And then the inside is going to have this kind of weird round edge.
01:26
I don't know how to say it.
01:28
All right.
01:28
So we're going to go around the x -axis.
01:30
So i'm going to assume that you're in the section where you're making disk or washers.
01:39
So i'm going to slice it perpendicular to the axis.
01:43
We're rotating around.
01:44
Okay.
01:44
And so that little slice is going to go around and it's going to make a washer...