00:01
We're given this function f of x, and for part a of our question, we're going to try to find the derivative of our function at x is equal to negative 1.
00:10
And so the first thing that we're going to do is find the derivative of our function.
00:15
So f prime of x is equal to...
00:19
We're going to use the power rule to find this derivative.
00:23
And what we do is we take down the exponent, and we multiply it by our x and our whatever x is multiplied.
00:30
By it in this case two, and then we minus 1 to our exponent.
00:34
So we're going to have 3 times 2, which is 6 times x to the 3 minus 1 exponent, which is 2.
00:42
And we're going to do the same thing for 3x squared, and in that case we get 6x.
00:47
And then as for our constant, when we take the derivative of a function, all constants go to 0.
00:53
So this negative 2 just becomes 0.
00:56
And now that we found this derivative of our function, we can find the derivative at negative 1, which is equal to 6 times negative 1 squared plus 6 times negative 1, which is equal to 6 minus 6, which is equal to 0.
01:13
So our derivative at f is equal to negative 1 is equal to 0.
01:20
And now for part b, we're going to find the second derivative of our function f, and how we're going to do that is by finding the derivative of our first derivative.
01:29
So f double prime of x is equal to the derivative of 6x squared plus 6x.
01:37
And we're going to use the power rule again to find this derivative...