Question

What is the equation of a line that passes through (2, -1) and is perpendicular to the line 2x-y=1

Answer 1

first step:  find slope of line

2x - y = 1

2x = y + 1

y = 2x - 1

slope of line:  2

perpendicular to slope of line:  - 1/2

now we want the equation of the line passing through (2, -1) with slope = -1/2

y - y1 = m (x - x1)  (point-slope form)

y - -1 = (-1/2) (x -2)

y + 1 = (-1/2)x + 1

y = (-1/2)x