(1,7) and perpendicular to the line 3x + 9y=18

Question

Write a slope intercept equation for a line with the given characteristics containing the point (1,7) and perpendicular to the line 3x + 9Y=18

Answer 1

containing the point (1,7) and perpendicular to the line 3x + 9Y=18

 

For line  ax + by = c  the slope is m = -a/b

The slope of 3x + 9y = 18 is -3/9 = -1/3

A perpendicular line will have a slope of -1/m = -1/(-1/3) = 3

 

You want the equation of a line with slope m = 3 containing (1, 7)

 

y = mx + b

y = 3x + b

Using (1,7) as (x,y) find b

7 = 3 + b

b = 4

 

y= 3x + 4