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. So that's going to be the slope of this line, of L of x is f prime of four. Let me make that clear. So this right over here is the slope, the slope when x is, at x equals four. So it's the slope of this entire line. And so any other point on this, it's going to be f of four plus the slope times how far you are away from x equals four. So it's going to be times x minus four.