Question

(09.02)

Solve x2 - 8x - 20 = 0. (1 point)
x = 4, x = -5
x = -4, x = 5
x = 2, x = -10
x = -2, x = 10

Answer 1

x = - 2, x = 10

Explanation:

Given

x² - 8x - 20 = 0

Consider the factors of the constant term (- 20) which sum to give the coefficient of the x- term (- 8)

The factors are - 10 and + 2 , since

- 10 × 2 = - 20 and - 10 + 2 = - 8 , then

(x - 10)(x + 2) = 0

Equate each factor to zero and soilve for x

x + 2 = 0 ⇒ x = - 2

x - 10 = 0 ⇒ x = 10