00:01
For this problem, we want to find the length of a curve.
00:04
So we want to use our arc length formula.
00:07
So for here, we're given that x is equal to 1 over 3, y to the 3 halves, minus y to the 1 half.
00:21
We want to look at y is equal to 1 to y is equal to 9.
00:29
So for arc length, we first want to start by computing our derivative.
00:33
So here we're looking at d x, d y.
00:39
That's going to be equal to 1 over 3 times 3 halves y to the 1 half, minus 1 half y to the negative 1 half.
00:54
And we can simplify this and we see that we get 1 half y to the power of 1 half minus y to the power of negative 1 half.
01:11
So we want to go ahead and square this derivative.
01:17
It'll make things easier in the problem.
01:20
If we square it now.
01:27
So if you go through the steps to foil this, you'll find that it's equal to 1 over 4 y minus 2 plus 1 over y.
01:48
So now we can plug this into our arc length formula.
01:51
So we're looking at integral from 1 to 9 of the square root of 1 plus our derivative squared.
02:05
So 1 fourth times a quantity y minus 2 plus 1 over y.
02:15
We're integrating with respect to y.
02:19
So we can combine this.
02:21
If we notice that 1 is equal to 1 over 4 times 4.
02:40
So that means we can move this 4 and combine it with the negative 2...