Question

Write a slope intercept equation for a line passing through the point (4,-2) that is parallel to the line 4x+5y=7. Then write a second equation for a line passing through the point (4,-2) that is perpendicular to the line 4x+5y=7

Answer 1

First, the equation needs to be put into slope-intercept form, which is y = -4/5x + 7/5. Then, you need to know what parallel and perpendicular lines are. REMEBER, parallel lines have the same slope, and perpendicular lines have slopes whose product equal -1. You just need to substitute. For the parallel line, -2 = -4/5(4) + b, and b = 6/5, so y = -4/5x + 6/5. For the perpendicular line, the slope is 5/4. Now substitute. -2 = 5/4(4) + b, and b = -7, so y = 5/4x -7.