19) Let $g$ be the function given by $f(x)=\int_{1}^{x}\left(3 t-6 t^{2} ight) d t$. What is the $x$-coordinate of the point of inflection of the graph of $\mathrm{f}$ ? (a) $-\frac{1}{4}$ (b) $\frac{1}{4}$ (0) 0 (d) $\frac{1}{2}$CS.SD. 121||