System of linear equations

Question

The solution of a system of linear equations is (2, -4). One equation in the system is 2x + y = 0. Explain how you could find a second equation for the system. Then find a second equation.

Answer 1

y = -2x

The perpendicular line passing through the same point would have a slope of 1/2.

y + 4 = (1/2)(x -2)

y + 4 = (1/2)x - 1

(1/2)x - y = 5