Find an expression for the cubic function f if f(1) = 6 and f(-1) = f(0) = f(2) = 0.
Answer is apparently f(x) = -3x (x+1) (x-2) but I just don't understand this problem.
You're given the roots which means that you should be able to write down the factors. Then the equation is f(x) = a(x - [-1])(x - 0)(x - 2), that is, f(x) = a(x + 1)x(x - 2).