Question

A system of equations is given.

​y= x^2 −9
y= −2x−1

​What is one solution to the system of equations?

Answer 1

(- 4, 7 ) and (2, - 5 )

Step-by-step explanation:

Given the 2 equations

y = x² - 9 → (1)

y = - 2x - 1 → (2)

Substitute y = x² - 9 into (2)

x² - 9 = - 2x - 1 ( subtract - 2x - 1 from both sides )

x² + 2x - 8 = 0 ← in standard form

(x + 4)(x - 2) = 0 ← in factored form

Equate each factor to zero and solve for x

x + 4 = 0 ⇒ x = - 4

x - 2 = 0 ⇒ x = 2

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

x = - 4 → y = - 2(- 4) - 1 = 8 - 1 = 7 ⇒ (- 4, 7 )

x = 2 → y = - 2(2) - 1 = - 4 - 1 = - 5 ⇒ (2, - 5 )

Answer 2

(-4,7)

Step-by-step explanation:

I graphed the two equations with a graphing tool.

The first equation forms a parabola.

The second equation is linear.

The graphed equations intercept at two points. Since the question asked for one, then one solution of the system is (-4,7).