Determine the equation of the lines (a) parallel to and (b) perpendicular to the line 4y - x = 20 and containing the point (2,-3)

Question

Determine the equation of the lines (a) parallel to and (b) perpendicular to the line
4y - x = 20 and containing the point (2,-3)

Answer 1

The line relative to which you're working has slope m = ¼   (from 4y = x + 40, then divide all by 4).

 

So in a), the parallel line will have this same slope.  Now use "point slope" form to write the equation desired.

 

And in b), the perpendicular line must have slope -4 (negative reciprocal of the slope of the 'other (perp.) line).

To finish this job, use "point slope" form again.