1. The problem statement, all variables and given/known data What the title says. There's a b part to the problem, but of course I can't move on to it until I understand what is going on here. 2. Relevant equations A third degree polynomial is of the form f(x) = ax3 + bx2 + cx + d This information was not given in the question, but I'm assuming that it is necessary for solving this question. 3. The attempt at a solution I tried substituting the roots into the function ( f(-3), f(-1) and f(2)), but soon realized, that I have 4 unknowns to deal with, not 3, so that wasn't gong to cut it. f(-3) = -27a + 9b -3c + d f(-1) = -a + b - c + d f(2) = 8a + 4b + 2c + d That annoying constant d is what I can't deal with, with just these 3 equations. The answer at the back of the book states that any equation of the form f(x) = a(x+3)(x+1)(x-2) would suffice, but apparently I don't understand the theory of polynomials well enough to get how they came to this conclusion. I see the coefficient a , but where are the coefficients b and c, and the constant d? How can they just ignore them, or did they? What am I missing here?