00:01
Okay, so for this problem, we want to use newton methods to find the roots of this function here.
00:08
So this function is 2x minus x square plus 1.
00:18
So it's a parabola.
00:19
So if we plot it, i'm going to do that again.
00:26
If we try to plot it, it should look something like this.
00:35
This is a parabola.
00:37
If you want to find the roots, you don't need to use newton's method.
00:41
You could easily find the formula, which is x equals minus b plus and minus the square root of b square minus 4a over 2a.
00:57
You could use that formula if you wanted, but let's try to see with newton's method what we find.
01:04
So what is newton methods? newton method is, let's just put that in parentheses since we won't be using it.
01:14
Newton's method is simply xn plus 1 equals to xn minus f of xn over f prime or x n.
01:38
So the derivative of f.
01:39
So we need to compute the derivative of f if we want to solve this problem.
01:46
What's the derivative of f? f prime of x.
01:51
Well, this is a polynomial, so it's very easy to find its derivative.
01:56
So the derivative of 2x is 2.
01:59
The derivative of minus x squared is minus 2x.
02:03
We simply drop the 2 and the derivative of 1 is 0.
02:07
So we have f prime of x.
02:09
And we can simply do nuisance method.
02:12
So we're given 2x0.
02:15
So if we use x0 equals 0, that means that x1 is equal to 0.
02:28
So we use that formula here, 0 minus f of 0 over f prime of 0, which is 0 minus 0, 2 times 0 minus 0 plus 1.
02:54
So we have 1 on the numerator.
02:57
And on the denominator, we have 2 minus 2 times 0.
03:01
So 2, which is simply minus 1 .5 or minus 1 over 2.
03:11
Not minus 1 .5 minus 0 .5...