f(x) = x2 + bx + c The equation f(x) = 0 has two distinct roots which are from the set {– 3, – 2, – 1, 0, 1, 2, 3}. How many different expressions of f(x) are possible such that f(0) is non-negative?

1) 3
2) 6
3) 12
4) Infinite