The graph of $f(x)=\frac{1}{3} x^{3}+\frac{1}{2} x^{2}-12 x-6$ looks something like this:
(FIGURE CANNOT COPY)
(a) Use a graphing utility to sketch an accurate graph of $f$
(b) Find the zero(s) of $f$ (the values of $x$ for which $f(x)=0$ ) accurate to three decimal places.
(c) Find the coordinates of the points marked $A$ and $B,$ accurate to three decimal places.