Question

A pair of perpendicular lines intersect at the point (7,1). Write the equation of the line that is perpendicular to the line that also passes through the point (-1,-3).​

Answer 1

If a line passes through both points (7,1) and (-1,-3), we can find the equation of the line by doing rise over run, or y/x. Y ends up going up 4 units, so y = 4, and x goes up 8 units, so x = 8. When you plug these into y/x, you get 4/8, or 1/2. The slope equation is y = 1/2x + b. The y-intercept is -2.5 because when x goes up by 1, y goes up by 1/2. So the equation is y = 1/2x - 2.5.