Question

Write an equation of the line that passes through (7, 10) and is perpendicular to the line y = 1x – 9.

Answer 1

y = - x + 17

Explanation:

The equation of a line in slope- intercept form is

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

y = x - 9 ← is in slope intercept form

with slope m = 1

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

`m_(perpendicular)` = -
`(1)/(m)` = -
`(1)/(1)` = - 1 , thus

y = - x + c ← is the partial equation

To find c substitute (7, 10) into the partial equation

10 = - 7 + c ⇒ c = 10 + 7 = 17

y = - x + 17 ← equation of perpendicular line