1. Writing Rules for Linear Functions

2. We compared slopes across three different representations – graphs, tables, and in equations. Functions are similar, in that they can be represented by words, tables and or graphs.

3. Writing a Function Rule From WORDS Start by translating the information into an equation. Suppose the rate for a cell phone plan is $30 a month plus $0.05 per text. Write a function rule to represent the total monthly cost. Total monthly cost = $30 + $0.05 per text let y = total monthly cost let x = the number of texts y = 30 + 0.05xy = 0.05x + 30

4. ON YOUR OWN Start by translating the information into an equation. A school is having a field trip. The cost of the field trip is $350 for the bus, plus $7 per student. Write a function rule to represent the total cost of the field trip. Total cost of field trip = $350 + $7 per student let y = total cost of field trip let x = the number of students

5. Find the changes in the inputs and outputs Writing a Function Rule from a TABLE X036 9 12 15 Y108 6 4 2 0 The table has a coordinate with an x value of 0, (0,10). This point lies on the y-axis and is the y-intercept.

6. Do the values in the tables represent a linear function? If so, write a function rule. ON YOUR OWN X012 3 4 5 Y24 6 8 10 12 Yes No y = 2x + 2 X024 6 8 10 Y36 12 15 18 20

7. Find the slope Writing a Function Rule from a GRAPH See if the line crosses to y-axis, to see if you can locate the y-intercept If not, use the equation, insert equation, to calculate the y-intercept.

8. Find the slope ON YOUR OWN Find or calculate the y-intercept.