00:01
What they mean by log differentiation is, let me just write all this down, cosine cubed of x, sine cubed of x, all over 2x cubed plus 1 squared, is to take the natural log on both sides.
00:21
You might be curious, why would we do that? well, now you could actually use your log laws, and you can split this up.
00:33
So the natural log of cosine and one of the log laws is you can take this exponent and move it in front the other one is with a multiplication you can split it up using addition and then with division you can split that up using subtraction subtraction in there and move that two in front 2x cubed plus one so what do we have is a derivative of the left sides 1 over y dy dx x.
01:03
This next one, the 3 is there.
01:06
The derivative of natural log is 1 over cosine.
01:09
And then you take the derivative of cosine, which is negative sine.
01:14
And then here, same thing, 1 over sine.
01:18
The derivative of sine is cosine.
01:22
And then here, it's 1 over 2x cubed plus 1, but then the derivative of the inside, which is 6x squared.
01:31
And then what you'd want to do is move this y to the other side.
01:37
And remember, y is equal to what we had started with...