Answer:
a
Step-by-step explanation:
Given
x² + 20x + 100 = 36 ( subtract 36 from both sides )
x² + 20x + 64 = 0 ← in standard form
Consider the factors of the constant term ( + 64) which sum to give the coefficient of the x- term ( + 20)
The factors are + 16 and + 4, since
16 × 4 = + 64 and 16 + 4 = + 20, hence
(x + 16)(x + 4) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 16 = 0 ⇒ x = - 16
x + 4 = 0 ⇒ x = - 4
