F(x) = x5 − 8x4 + 21x3 − 12x2 − 22x + 20 three roots of this polynomial function are −1, 1, and 3 + i. which of the following describes the number and nature of all the roots of this function? f (x) has two real roots and one imaginary root. f (x) has three real roots. f (x) has five real roots. f (x) has three real roots and two imaginary roots.