Answer:
x = - 4, x = - 3
Step-by-step explanation:
To find the zeros equate f(x) to zero, that is
x² + 7x + 12 = 0
To factorise the quadratic
Consider the factors of the constant term (+ 12) which sum to give the coefficient of the x- term (+ 7)
The factors are + 4 and + 3, since
4 × 3 = 12 and 4 + 3 = 7, hence
(x + 4)(x + 3) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 4 = 0 ⇒ x = - 4
x + 3 = 0 ⇒ x = - 3
