Question

What is the equation of a line that is perpendicular to 2x+y=-4 and passes through the point (2, -8)?

Answer 1

2x + y = -4
y = -2x - 4
differentiate:
y' = -2

m=-2 perpendicular = -1/m = -1/-2 = 0.5, x=2 y=-8

y=mx+c
-8=0.5(2) + c
-8 = 1 + c
-9 = c

y = .5x - 9

OR you can use y-y_1 = m(x - x_1), where x_1 = 2, y_1 = -8, m = 0.5
y - -8 = 0.5(x - 2)
y + 8 = 0.5x - 1
y = 0.5x - 9

same answer either way