Question

Solve the following system of equations.

Answer 1

D

Explanation:

y = x² - 4x - 5 → (1)

y = x - 9 → (2)

substitute y = x² - 4x - 5 into (2)

x² - 4x - 5 = x - 9 ( subtract x - 9 from both sides )

x² - 5x + 4 = 0 ← in standard form

(x - 1)(x - 4) = 0 ← in factored form

equate each factor to zero and solve for x

x - 1 = 0 ⇒ x = 1

x - 4 = 0 ⇒ x = 4

substitute these values into (2) for corresponding values of y

x = 1 : y = 1 - 9 = - 8 ⇒ (1, - 8 )

x = 4 : y = 4 - 9 = - 5 ⇒ (4, - 5 )