First note that there are an infinite amount of polynomials with roots x = 5, x = -4 and x = 1. They are only asking you for a polynomial with these roots. Isn't an obvious answer f(x) = (x-5)(x+4)(x-1)?
The problem is that we don't know what you know in order to answer your question! Do you know the "0 factor property": For number a, b, ab= 0 if and only if at least one of a, b is 0"? Do you know how to solve an equation like (x- 3)(x- 2)= 0?