00:01
I have graphed of graphs of y equals x and squared of y equals x or y equals x squared.
00:05
So when we're rotating that about the x -a -axis, we use partials of x.
00:17
So we have pi r squared minus pi r squared, so we have pi r squared of y equals x minus pi r squared of y equals x squared.
00:28
So we plug this in, expand it, integrate it, we get that to pi over 15 is our answer.
00:36
So when you rotate it about y, we have to use partials of y, so d y.
00:43
So we rotated it, get that, we expand it, we integrate it, and we get that y equals 5 over 6.
00:57
Now for our final question, we have to set up the integral about x equals 4.
01:05
So x equals 4 is parallel with a y -axis, so we're going to use parts of y again.
01:11
And we're still integrating from 0 to 1, so we can start with that.
01:15
We are also going to be doing the pyr squared, so we have 5 from 0 to 1.
01:20
The first r is going to be this equation for this line right here, which is just y equals x...