Zero of the functions f (x) = x^2 + 4x+3 and why?

There are two zeros: - 3 and - 1. This is because when you factor f (x) = x^2 + 4x + 3, it becomes f (x) = (x + 3) (x + 1). In order to find the zeros, set f (x) to 0, and then solve for x for both (x + 3) and (x + 1). You can check your answer by substituting either - 3 or - 1 for x in the equation 0 = x^2 + 4x + 3.