A

-intercept of a graph is a point at which the line or curve intersects the -axis. In this course, -intercepts are defined as points, so we denote them as a coordinate pair, , where is the -coordinate of the -intercept. The -coordinate of any -intercept will always be , since it must lie on the -axis, which is the line . Because of this, some resources let the -intercept refer to just the -coordinate or the point, in this case.An

-intercept of a graph is a point at which the line or curve intersects the -axis. In this course, -intercepts are defined as points, so we denote them as a coordinate pair, , where is the of the -intercept. The -coordinate of any -intercept will always be , since it must lie on the -axis, which is the line . Because of this, some resources let the -intercept refer to just the -coordinate or the point, in this case.One way to write the equation of a line is to use *slope-intercept form*. If we call the slope of a line and the -coordinate of its -intercept , then the equation of that line in slope-intercept form will be .

Two lines are called *perpendicular* if they form a angle. This will happen if their slopes are the negative reciprocals of one another. Put more mathematically, if a line has a slope of , then every line perpendicular to it will have a slope of .