2. Defining Success Define the relationship between quantities with emphasis on the rate of change and initial value Communicate precisely the meaning of rate and initial value in y = mx + b

3. WV Common Core State Standard Construct a function to model a linear relationship between two quantities. Determine the rate of change and initial value of the function from a description of a relationship or from two (x, y) values, including reading these from a table or from a graph. Interpret the rate of change and initial value of a linear function in terms of the situation it models, and in terms of its graph or a table of values. (CCSS Math.8.F.4)

4. In this lesson you will: Review rate of change and initial value Write equations that are modeled by tables, graphs, and situations Interpret the various data displays in the form of a real-life situation

5. Real-Life Situation The table below shows the cost of renting a car. The company charges $45.00 a day for the car as well as charging a one-time fee for the car’s navigation system (GPS). Write an expression for the cost in dollars, x, as a function of the number of days, y. Days (y)Cost (x) in dollars 170 2115 3160 4205

6. Solution y = 45x + 25 Where 45 represents the rate of change (slope) and 25 represents the initial value, y-intercept.