Find all the zeros of the function. When there is an extended list of possible rational zeros, use a graphing utility to graph the function in order to disregard any of the possible rational zeros that are obviously not zeros of the function.
1. f (x) = x3 − 16x2 + x − 16
2. f (x) = 4x4 − 12x3 − 71x2 − 3x - 18