Let's call that L of x. And then we can use that to, then we can evaluate that at 4.36. And hopefully that'll be a little bit easier to do than to try to figure out this right over here. So how would we do that? Well, one way to think about it, obviously there's many ways to express a line, but one way to think about it is, okay, it's going to, L of x is going to be, it's going to be, it's going to be f of four. It's going to be f of four, which is two. It's going to be f of four plus the slope, the slope at x equals four, which is of course the derivative, f prime of four.