Answer:
(x-1)(x+5)(x-3)
Step-by-step explanation:
By trial and error, while considering the factors of the constant i.e 15 which can be a zero of the polynomial we arrive at p(1) cos if x=1 then x-1 is a factor therefore divide the polynomial by (x-1) and you'll get a quotient of x^2+2x-15 and if we factorize that we'll get (x+5)(x-3)