00:01
Okay, in this function, f of x is equal to the square root of 1 minus 2x, and we want to find the derivative at a.
00:08
We are going to use the chain rule, which says the derivative of our function with respect to x, d, y, dx, equals the derivative of the function with respect to u times the derivative of u with respect to x.
00:34
U in this case is going to be the 1 minus 2x.
00:39
So we're taking the square root of 1 minus 2x or the square root of you.
00:43
So now i'm going to rewrite our function f of x as 1 minus 2x.
00:57
And instead of writing as the square root of 1 minus 2x, the square root is the same thing as raising to the 1 half power.
01:04
So, f of x can be rewritten as 1 minus 2x to the 1 half power.
01:18
Now, if this is f of x, we're now going to differentiate this function.
01:28
Now, if you think of this as the u, the derivative of u to the 1 half is 1⁄2 times u, which is this in parentheses, and then 1 half, you would have to subtract 1 from this exponential.
01:48
And see you would get one half minus one is negative one half.
01:53
So that's the derivative of u to the one -half.
02:00
It's one -half times you to the negative one -half.
02:03
But then it's a little hidden here.
02:06
We still have to do the derivative of you with respect to x.
02:10
Let me show you that...