Question

Write the equation of the line perpendicular to y = 1/3x + 12 that contains the point (- 9, - 1).

Answer 1

y = - 3x - 28

Explanation:

the equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

y =
`(1)/(3)` x + 12 ← is in slope- intercept form

with slope m =
`(1)/(3)`

given a line with slope m then the slope of a line perpendicular to it is

`m_(perpendicular)` = -
`(1)/(m)` = -
`(1)/((1)/(3) )` = - 3 , then

y = - 3x + c ← is the partial equation

to find c substitute (- 9, - 1 ) into the partial equation

- 1 = 27 + c ⇒ c = - 1 - 27 = - 28

y = - 3x - 28 ← equation of perpendicular line