Okay, so a general rule for finding perpendicular lines in the form of y = mx + b is y = (-1/m) + b. First, let's ignore b (-7) because we're going to find that later. A perpendicular line to y = 4x + b is y = -1/4x + b. Alright, so now let's plug in the values. They are in the form of (x,y), so let's plug them in accordingly.
3 = -1/4(4) + b 3 = -1 + b b = 4 y = -1/4x + 4 So a line perpendicular to y = 4x - 7 is y = -1/4x + 4.
