The point on the graph where a line crosses the y axis is called the y intercept (see Fig. 11-21 ).
To find the y intercept, let x = 0 and substitute in the equation, and then solve for y .
Find the y intercept of 2x + 3y = 9.
Substitute 0 for x and solve for y:
Hence, the y intercept is (0, 3).
The point on the graph where a line crosses the x axis is called the x intercept (see Fig. 11-22).
To find the x intercept, let y = 0 and substitute in the equation, and then solve for x .
Find the x intercept for 5x + 2y = 30.
Substitute 0 for y and solve for x:
Hence, the x intercept is (6, 0).
Math Note: It is easy to draw lines on a graph using the intercepts for the two points.
Intercepts Practice Problems
1. Find the x intercept of 5x + 4y = 30
2. Find the y intercept of x - 7y = 14
3. Find the y intercept of 2x + 8y = 24
4. Find the x intercept of 3x - 17y = 21
5. Find the y intercept of x + 5y = -20
1. (6, 0)
2. (0, -2)
3. (0, 3)
4. (7, 0)
5. (0, -4)
Practice problems for these concepts can be found at: Graphing Practice Test.
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