f(x) = (x - 1)(x - 2)(x - 3) ⇒ f(1) = f(2) = f(3) = 0 ∴ f(x) is not one-one. For each y e R, there exists x ∊ R such that f(x) = y. ∴ f is onto. Note that if a continuous function has more than one roots, then the function is always many-one.