00:03
All right, so we have a business application here, and the first thing we're asked to do is find the marginal cost, and the marginal cost is the derivative of the cost function.
00:12
So we take the derivative of the given function, and we get 3 plus 0 .02x plus 0 .006x squared.
00:24
For part b, we want to find the marginal cost for 100.
00:28
So we go ahead and we substitute 100 into this equation.
00:33
The numbers work out pretty nicely.
00:35
You could even do it without a calculator if you really wanted to.
00:43
And you end up with 11.
00:45
So what that means is if you've already made 100 items, that would be the cost to make the 101st item.
00:53
That's an estimate of it at least.
00:56
Using the derivative gives you an estimate...