Using Intercepts Holt Algebra I 5 2 LT

Using Intercepts Holt Algebra I – 5. 2 LT: F. IF. 5 - Relate the domain of a function to its graph and, where applicable, to the quantitative relationship it describes.

Brain Exercise (Warm-Up) Friday, 06 February 2015 Tayte explored the ocean floor 120 feet below the surface and then ascended at a rate of 30 feet per minute. How long does it take her to reach the surface from the ocean floor? 1. 2. 3. 4. Write a function. Graph the equation. Write the domain and range. What do (x, 0) and (0, y) represent to this story and on your graph ?

1. y = 30 x – 120 3. D: {0 ≤ x ≤ 4} R: {-120 ≤ y ≤ 0} 4. STORY: (x, 0) represents the time when Tayte reaches the water surface. (0, y) represents the elevation Tayte is at before she attempts to surface. GRAPH: (x, 0) represents the point where the graphed function touches the x-axis. (0, y) represents the point when the graphed function touches the y-axis.

x- & y-intercepts • The x-intercept is the coordinate of the point where a graphed function crosses the x-axis (x, 0). • The y-coordinate is always equal to 0. • The y-intercept is the coordinate of the point where a graphed function crosses the y-axis (0, y). • The x-coordinate is always equal to 0.

You can also do the “Cover It Up” method! • Simply cover the variable you Finding Intercepts DON’T want to know and solve. How to find the x-intercept • Replace y with 0, and solve for x. How to find the y-intercept • Replace x with 0, and solve for y. 1. 3 x – 2 y = 12 2. -3 x + 5 y = 30

Graphing Linear Equations by Using Intercepts • How do you find intercepts with the following equation? Multiply each side of the equation by the LCD to clear the fractions. Now, write the equation in Standard Form. Lastly, find the intercepts.

Questions to Answer 1. The school store sells pens for $2. 00 and notebooks for $3. 00. Write and graph an equation that describes the number of pens (x) and notebooks (y) that you can buy for $60. a) Find the intercepts. What does each intercept represent? b) What are the Domain and Range? 2. A bank employee notices an abandoned checking account with a balance of $384. The bank charges a $48 annual fee for the account (even after the account is empty). Write and graph the function. a) Find the intercepts. What does each intercept represent? b) What are the Domain and Range? c) When will the account be empty? 3. What is the difference between graphing a line and using intercepts and graphing a line by generating a table of ordered pairs?