Best linear approximation of parabola between 0 and d

Question

I am currently thinking about the following problem: given a parabola $f(x) = x^2$, what is the best linear approximation $g(x)$ of $f(x)$ between 0 and some $d > 0$? In my case, best approximation means that the maximum $|g(x) - f(x)|$ between 0 and $d$ is minimized.