Question

Find the slope and y-intercept of the line that is perpendicular to

y= —1/3x + 5 and passes through the point (—3, —7)

Answer 1

Slope =3; y-intercept = (0, 2)

Explanation:

y = -⅓x + 5

1. Calculate the slope of the perpendicular line

m₂ = -1/m₁

`m_(2) =-(1)/(-(1)/(3)) = \mathbf{3}`

2. Calculate its y-intercept

y = mx + b

-7 = 3(-3) + b

-7 = -9 + b

Add 9 to each side:

b = 2

The y-intercept is at (0, 2).

The diagram shows the graph of your original line in red. The perpendicular line in black passes through (-3, -7) with a y-intercept at (0, 2).