Slope of a line

Question

The slope of a line that is perpendicular to (2,4) (-1,0) is?

Answer 1

slope of the line m = (y₂-y₁)/(x₂-x₁)

Replace y₂ = 0, y₁ = 4, x₂ = -1 ans x₁ = 2 in the slope formula

m = (0 - 4) / (-1 - 2)

m = -4/-3

m = 4/3

The lines are perpendicular, so their slopes product is -1

Perpendicular line slope = -1/m = -1(4/3) = -3/4.

Answer 2

Let (x1,y1) = (2,4)

    (x2,y2) = (-1,0)

Slope of the line m1 = 0-4/-1-2

                             = -4/-3

                             = 4/3

Perpendicular line slope =m2

m1m2 = -1

4/3m2 = -1

Apply multiplication property,multiply by 3/4 to each side.

4/3*3/4m2 = -1*3/4

⇒m2 = -3/4