Unit 2 Day 3: Graphing Using Slope-Intercept Form Essential Questions: What is the slope-intercept form of a line? How do we use it to graph the line?

Vocabulary y-intercept: the point (0 , y) where an equation crosses the y-axis, represented with the letter b Slope-Intercept Form: y = mx + b m = slope b = y- intercept

y-intercept: (0 , 1) y-intercept: (0 , 2) Example 1: Identify the y-intercept from each of the graphs. y-intercept: (0 , 1) y-intercept: (0 , 2)

y-intercept: (0 , -5) y-intercept: (0 , 0) Example 2: Identify the y-intercept from each of the graphs. y-intercept: (0 , -5) y-intercept: (0 , 0)

y-intercept: y-intercept: c. y = x - 2 d. y = x - 13 Slope: Slope: Example 3: Identify the slope and the y-intercept in each equation. a. y = 4x + 2 b. y = -x - 3 Slope: Slope: y-intercept: y-intercept: c. y = x - 2 d. y = x - 13 Slope: Slope: 4 -1 (0 , 2) (0 , -3) 1 2 1 2 1 (0 , -2) (0 , -13)

Graphing Using y = mx + b Plot the y-intercept as your first point. To get your other points, count out the slope from the y-intercept in both directions. Remember, a whole number as a slope ALWAYS has a “run” of 1! Slope y-intercept

Example 4: Graph each line using y = mx + b. y = -2x + 3 Slope: y-intercept: -2 1 (0 , 3) 3 2 y = x - 4 Slope: y-intercept: 3 2 (0 , -4)

Example 5: Graph each line using y = mx + b. y = 3x - 5 Slope: y-intercept: 3 1 (0 , -5) 2 3 y = - x + 4 Slope: y-intercept: 2 3 - (0 , 4)

Example 6: Graph each line using y = mx + b. -2 1 2x + y = 4 Slope: y-intercept: -2x -2x y = -2x + 4 (0 , 4) 2 3 3y - 2x = 6 Slope: y-intercept: +2x +2x 3y = 2x + 6 3 3 3 (0 , 2) y = x + 2 2 3

Summary Essential Questions: What is the slope-intercept form of a line? How do we use it to graph the line? Take 1 minute to write 2 sentences answering the essential questions.