Question

Find the equation of the line through point (-1, 2) which is perpendicular to y = 5x -1

Select one:

5y = x + 11

5y = - x + 11

5y = x -11

5y = -x - 11

Answer 1

Perpendicular lines are lines that intersect at right angles; lines are perpendicular if the product of their slopes is "-1".

The slope of the given line is "5", so a perpendicular line will have a slope of -1/5.  If the perpendicular line we are looking for goes through the point (-1,2), we have:

2 = (-1/5)(-1) + b    =>  b = 9/5

So the equation of the perpendicular line is: y = -(1/5)x + (9/5)

Or:  5y = -x + 9

I stand by my answer!