Chapter 6 Lesson 2 Slope-Intercept Form

Define: Slope-Intercept Form Define: Slope-Intercept Form The slope-intercept form of a linear equation is y = mx + b m represents the slope b represents the y-intercept

Slope-Intercept Form y = -4x + 3 y = 5 – x y = x y = 5 Name the slope and y-intercept of each equation : m = -4, b =3 m = -, b = 5 Rewrite as y = x + 0, m =, b = 0 Rewrite as y = 0x + 5, m = 0, b = 5

Slope-Intercept Form 8x + y = 4x - 2y =10 Name the slope and y-intercept of each equation : Rewrite as y = -8x, m = -8, b = Rewrite as y = 2x - 5, m = 2, b = -5

Where we are and where we’re going! TODAY… 1.Write the equation of a line given a. Slope and y-intercept b. Graph 2.Use the slope and y-intercept to graph a line LATER… Write the equation of a line given: - Slope and one point - Two points - x - and y-intercepts

1. Write the Equation of the Line given a. Slope and y-intercept m = -3, b = 1 m = -2, b = -4 m = 0, b = 10 m = 1, b = 0 m = 0, b = 0 ● Substitute m and b into y = mx + b y = -3x + 1 y = -2x - 4 y = 0x + 10, y = 10 y = 1x + 0, y = x y = 0x + 0, y = 0

1. Write the Equation of a Line given b. Graph Find the y-intercept from the graph. Count the slope from the graph. To write the equation of the line, substitute the slope and y-intercept in the slope-intercept form of the equation.

Example 1 b = -3 m = y = x - 3 x y +2 +3

Example 2 b = 1 m = y = x + 1 x y

Example 3 b = 4 m = 0/1= 0 y = 0x + 4, y = 4 x y

2. Use the slope and y-intercept to graph the line x y What is the y-intercept. Where does it cross the y-axis? ___ What is another point on the line? ___ What is the slope from the y-intercept to the other point? ____ What is the equation given the y-intercept and the slope? ______

2. Use the slope and y-intercept to graph the line x y What is the y-intercept. Where does it cross the y-axis? ___ What is another point on the line? ___ What is the slope from the y-intercept to the other point? ____ What is the equation given the y-intercept and the slope? ______

2. Use the slope and y-intercept to graph the line x y Graph y=-3/2x -1 Start with the y-intercept. Use the slope to graph the next point. Connect the points with a line.

2. Use the slope and y-intercept to graph the line x y Graph y=-1/4x +5 Start with the y-intercept. Use the slope to graph the next point. Connect the points with a line.

Summary of Today’s Lesson You should be able to: ◦Write a linear equation given the y-intercept and slope ◦Write a linear equation given a graph ◦Graph a linear equation