Answer:
x = - 5, x = 3
Step-by-step explanation:
To find the x- intercepts equate f(x) to zero, that is
x² + 2x - 15 = 0 ← in standard form
Consider the factors of the constant term ( - 15) which sum to give the coefficient of the x- term ( + 2)
The factors are + 5 and - 3, since
5 × - 3 = - 15 and 5 - 3 = + 2, hence
(x + 5)(x - 3) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 5 = 0 ⇒ x = - 5 ⇒ (- 5, 0 ) ← x- intercept
x - 3 = 0 ⇒ x = 3 ⇒ (3, 0 ) ← x- intercept
