4-1 Slope Intercept Form Word Problems Goals: Graph and interpret equations in slope-intercept form that model real life situations. Use a graphing calculator to graph linear equations. Eligible Content: A1.1.2.1.1 / A1.1.2.1.3 / A1.2.1.1.1 / A1.2.1.2.1 A1.2.1.2.2 / A1.2.2.1.3 / A1.2.2.1.4

Vocabulary Slope is rate of change y-intercept is the beginning amount

Example #1 The graph shows the number of cookies left on a plate after time has passed at a party. Find the slope and tell what it reveals about the situation. Find the y-intercept and tell what it reveals about the situation.

Example #2 The equation h = ½ t + 24 models changing river heights. h represents the height of the river (in feet) and t represents the time (in hours) since the flooding began. What does the slope of the equation reveal about this situation? What does the y-intercept of the equation reveal about this situation?

Example #3 The equation s = 15t + 25 models changing speeds of a car as it enters an expressway. s represents the speed of the car (in miles per hour) and t represents the time (in minutes). What does the slope of the equation reveal about this situation? What does the y-intercept of the equation reveal about this situation?

Using the calculator Equations must be in slope intercept form. Press Y= button Type in equation Press GRAPH button To change the x and y axes press WINDOW

Examples Graph each equation on your calculator: y = 3x + 4 2x + y = 8 3x – 2y = 10

Examples from earlier Graph each of the word problems from earlier in class: River: y = ½ x + 24 Car: y = 15x + 25

Homework None 