(a) use a computer algebra system to differentiate the function, (b) sketch the graphs of f and f’ on the same set of coordinate axes over the given interval, (c) find the critical numbers of f in the open interval, and (d) find the interval(s) on which f is positive and the interval(s) on which it is negative. Compare the behavior of f and the sign of f’. f(x) = -3 sin x/3, [0, 6π]