Chapter 5 - Linear Functions - 5-6 Parallel and Perpendicular Lines - Practice and Problem-Solving Exercises - Page 331: 21

$y= -1/5x-9/5$

perpendicular to $y = 5x+4$ and passes through (1, -2) A line perpendicular to $y=5x+4$ would have a slope of -1/5 since two perpendicular lines would have a product (for their slopes) of -1. ($5*-1/5 = -1$) $y=-1/5*x+b$ $-2 = -1/5*1+b$ $-2 = -1/5+b$ $-10/5 + 1/5 = -1/5+b+1/5$ $-9/5 = b$ $y= -1/5x-9/5$