*horizontal axis*(also called the

*x*

*-axis*) and the

*vertical axis*

*(also called the*

*y*

*-axis*). The place where these two axes (plural of axis) cross is called the

*origin*.

*Plotting a point* (finding and marking its location) on a graph isn’t much harder than finding a point on a number line, because a graph is just two number lines put together.

Every point on a Cartesian graph is represented by two numbers in parentheses, separated by a comma, called a set of *coordinates*. To plot any point, start at the origin, where the two axes cross. The first number tells you how far to go to the right (if positive) or left (if negative) along the horizontal axis. The second number tells you how far to go up (if positive) or down (if negative) along the vertical axis.

*A, B, C,*and

*D*:

*A* = (2, 3) *B* = (–4, 1) *C* = (0, –5) *D* = (6, 0)

The above figure depicts a graph with these four points plotted. Start at the origin, (0, 0). To plot point *A*, count 2 spaces to the right and 3 spaces up. To plot point *B*, count 4 spaces to the left (the negative direction) and then 1 space up. To plot point *C*, count 0 spaces left or right and then count 5 spaces down (the negative direction). And to plot point *D*, count 6 spaces to the right and then 0 spaces up or down.