Question

When solving for x, what is x squared plus 15 equals -8x

Answer 1

Answer:

x = - 5, x = - 3

Step-by-step explanation:

Given

x² + 15 = - 8x ( add 8x to both sides )

x² + 8x + 15 = 0 ← in standard form

Consider the factors of the constant term (+ 15) which sum to give the coefficient of the x- term (+ 8)

The factors are 5 and 3, since

5 × 3 = 15 and 5 + 3= 8, thus

(x + 5)(x + 3) = 0 ← in factored form

Equate each factor to zero and solve for x

x + 5 = 0 ⇒ x = - 5

x + 3 = 0 ⇒ x = - 3