X – Y INTERCEPTS

Concept: A coordinate graph is a system for finding the location of a point, or several points, on a flat surface called a plane. A coordinate graph is formed from two axis lines that cross at a point called the origin. The horizontal line is the x-axis and the vertical line is the y-axis. Both lines are marked as number lines with the origin at zero. The axes divide the graph into four quadrants, labeled I, II, III, and IV.

Each point on the grid is named by two numbers, an x-coordinate and a y-coordinate. The x-coordinate is always written first; the y-coordinate is always written second. Together the coordinates are called an ordered pair and are enclosed in parentheses, separated by a comma like this: (x, y) .

The point at which a line intersects the X-axis is called the X Intercept. The point at which a line intersects the Y-axis is called the Y Intercept. The X Intercept and the Y Intercept are both named by an ordered pair, just like any other point on a coordinate graph. An X Intercept point always has a y-coordinate of 0. A Y Intercept point always has an x-coordinate of 0.

Step for Finding X and Y Intercepts

Step 1 | Determine if the problem is asking for an X or a Y Intercept.
Step 2 | If the problem is asking for an X intercept, follow the line until it intersects with the X-axis.
Step 3 | Name the ordered pair for that point.
Step 4 | If the problem is asking for a Y intercept, follow the line until it intersects with the Y-axis.
Step 5 | Name the ordered pair for that point.
Step 6 | Write the final answer.

Example: Find the Y-Intercept.

Step 1 | Determine if the problem is asking for an X or a Y Intercept. | The problem is asking for a Y Intercept.
Step 2 | If the problem is asking for an X intercept, follow the line until it intersects with the X-axis. | Does not apply.
Step 3 | Name the ordered pair for that point. | Does not apply.
Step 4 | If the problem is asking for a Y intercept, follow the line until it intersects with the Y-axis. |
Step 5 | Name the ordered pair for that point. | (0, - 7)
Step 6 | Write the final answer. | The y intercept is (0, - 7)