00:08
I'm going to find the derivative of this function, so we're going to do the limit.
00:14
Each approach is 0 of r of x plus h minus r of x all over h.
00:25
So we have r of x right here.
00:28
That's going to go in there.
00:30
And we need to figure out r of x plus h.
00:37
So we put x plus h in 4x into the function and we have the limit each approach is zero of the r of x plus h minus the r of x all over h so we're going to multiply this function by the conjugate of the numerator which is our x plus h minus 5 plus our x plus or x minus 5 and we're going to multiply top and bottom by that.
01:31
So basically what we're doing is we're multiplying by 1 because when your numerator or equal you're multiplying by 1.
01:45
Okay, so the denominator i'm just going to leave as h times all of this.
01:57
The numerator i'm going to foil.
02:00
So first, that radical times that radical will give us just x plus h minus 5.
02:07
Now the outers and the inners are going to cancel.
02:12
Outers are this, positive, two radicals multiplied together...