1. Objective The student will be able to: 1.Find the x- and y-intercepts of linear equations. 2.Use the intercepts to make a “quick graph” of the linear function. NCSCOS: 1.02 & 3.03 Designed by Skip Tyler, Varina High School, edited by Leigh Harris, South Lenoir High School

2. What does it mean to INTERCEPT a pass in football? The path of the defender crosses the path of the thrown football. In algebra, what are x- and y-intercepts?

3. What are the x- and y-intercepts? The x-intercept is where the graph crosses the x-axis. The y-coordinate is always 0. The y-intercept is where the graph crosses the y-axis. The x-coordinate is always 0. (2, 0) (0, -6)

4. Find the x- and y-intercepts. 1. x - 2y = 12 x-intercept: Plug in 0 for y. x - 2(0) = 12 x = 12; (12, 0) y-intercept: Plug in 0 for x. 0 - 2y = 12 y = -6; (0, -6)

5. x-intercept: Plug in 0 for y. -3x - 5(0) = 9 -3x = 9 x = -3; (-3, 0) y-intercept: Plug in 0 for x. -3(0) + 5y = 9 5y = 9 y = ; (0, ) Find the x- and y-intercepts. 2. -3x + 5y = 9

6. x-intercept: Plug in 0 for y. Does 0 = 7? No! There is no x-intercept. None What type of lines have no x-intercept? Horizontal! Remember VUXHOY! (what’s that, you say? just wait...I’ll tell you in a minute...) Horizontal lines…y = 7…y-int = (0, 7) Find the x- and y-intercepts. 3. y = 7 ***Special case***

7. y-intercept: Plug in 0 for x. Does 0 = 9? No! There is no y-intercept. None What type of lines have no y-intercept? Vertical! Remember VUXHOY! (hmmmmmm...there’s that word again....patience...!) Vertical lines…x = 9…x-int = (9, 0) Find the x- and y-intercepts. 4. x = 9 ***Special case***

8. “VUXHOY” (this will really be helpful later!!!) Remember the word “VUXHOY” (this will really be helpful later!!!) Vertical lines Undefined slope (no slope) X = number; This is the equation of the line. Horizontal lines O - zero is the slope Y = number; This is the equation of the line.

9. What is the x-intercept of 3x – 4y = 24? 1.(3, 0) 2.(8, 0) 3.(0, -4) 4.(0, -6)

10. What is the y-intercept of -x + 2y = 8? 1.(-1, 0) 2.(-8, 0) 3.(0, 2) 4.(0, 4)

11. What is the y-intercept of x = 3? 1.(3, 0) 2.(-3, 0) 3.(0, 3) 4.None

12. What is the x-intercept of y = 3? 1.(3, 0) 2.(-3, 0) 3.(0, 3) 4.None

13. Find the x- and y-intercepts of 2x + 3y = 6 using the TI-84 graphing calculator. Before using the calculator, you MUST solve the equation for y first. 3y = -2x + 6 y = + 2 Type the equation in the “y =“ menu and graph it.

14. Your graph should look like this. It may vary depending on your window size. The x-intercept is (3, 0) Press 2 ND, TABLE and scroll to find where the y-value is zero to find the x- intercept.

15. Now find the y-intercept! Press 2 ND TABLE (or you may still be there) to find the y-intercept. y-intercept = (0, 2)