So parallel lines have the same slope, but perpendicular lines have negative reciprocal slopes. So a slope of 3/2 will have a negative reciprocal of -2/3. -x + 2y = 4 2y = x + 4 2y/2 = (x + 4)/2 y = 1/2 x + 2 m = 1/2, so reciprocal is -2/1 = -2 point (-2, 1) point-slope form: y-y1 = m (x-x1) y-1 = -2 (x- -2) y-1 = -2 (x+2) y-1 = -2x -4 y = -2x - 3, or: 2x + y = -3
