00:01
All right, we need to come up with the equation of the tangent line.
00:05
Any time you're asked to find the equation with tangeline, you need a point and a slope.
00:10
Well, they do give you the point in the problem.
00:13
That's the order to pair 1 -1.
00:15
Now, the slope is the derivative when you plug 1 in for x.
00:20
So you have to figure that out.
00:21
So as they're looking at this, they give us f of x is equal to 2x cubed minus.
00:34
It's 2x squared plus 1.
00:40
And you can verify that this is the correct point because if you plug in ones and for all these xes, you get 2 minus 2 plus 1.
00:47
So you do get the right y coordinate.
00:49
But what we need to do first is find the derivative.
00:53
And that's multiplying the exponent in front...