To write an equation in point-slope form given a graph of that equation first determine the slope by picking two points. Write equations of parallel lines and perpendicular lines by finding the line that passes through a point and has either parallel slope or perpendicular slope to the graph of a given equation. Find the slope m.
Y - y1 m x - x1 where m is the slope of the line x1 y1 is a point on the line and x y is any other point on the line.
Write the equation in slope-intercept form y. It emphasizes the slope of the line and a point on the line that is not the y-intercept. Enter coordinates xA yA x A y A of two point A and the coefficient for the slope m in the box. We know that the equation of a line is given by y-y1 m x x1.