And as we can see, as we get further and further from x equals negative one, the approximation gets worse and worse. But if we stay around x equals negative one, well, it's a decent, it is as good as you can get for a linear approximation, or at least in this example, it is a very good linear approximation. So when people say, hey, find a linear approximation of f around x equals negative one, or if they say, what is the following is the best approximation, and all of your choices are lines, well, essentially they're asking you to find the equation of the tangent line at x equals negative one. So let's do that. So in order to find the equation of the tangent line, the equation of a line is y is equal to mx plus b, where m is the slope and b is the y-intercept. There's other ways that you could think about it. You could think about it in terms of point slope, where you could say y minus some y that sits on that line is equal to the slope times x minus the corresponding x one.