Question

Find all zeros of the polynomial function f(x)=(x^3+2x^2−15x)⋅(x^2+2x−4)
(exact answers not decimal approximations)

Answer 1

Factor x out of the first expression. Obviously x = 0 is one root (or zeros of the polynomial)
See if you can factor each of the quadratic expression.
If not find the zeros using the quadratic formula.

Since this is fifth degree polynomial you should have a total of 5 roots.