00:01
We have this integral here, if 1 plus 2xy, as x goes from y squared over 4 to 2 squared of y, and then y goes from 0 to 4.
00:16
So what's that region look like? well, x equals y squared over 4 is this function here, and x equals 2 times a square to y is this function here.
00:28
And x equals 2 times a square to y is this function here.
00:30
So we can invert those and get y as a function of x.
00:33
We just get these.
00:35
So we get this airfoil like shape again that we had seen previously.
00:40
So here in this case, we're integrating respect to x first.
00:43
So we get x plus 1 plus x times 1 plus x, y, evaluated between our about limits here.
00:51
Plugging those in, we get this expression, which we can expand out as powers in y, and simply integrate that between 0 and 4, and we wind up with the value of 48.
01:02
Now to switch the order of integration, we need to invert these relationships here.
01:06
So y is going to go from, this is x squared over 4, and this is 2 times a squared of x.
01:15
So those are the bounds on y...