Warm-Up 6 minutes 1) Write the equation of the line with slope -2 and y-intercept 6. 2) Write the slope-intercept form of the equation for the line with slope 7 containing the point (3,8). 3) Write the slope-intercept form of the equation for the line containing the points (9,2) and (3,5).

7.7 Fitting Equations to Data 7.7 Fitting Equations to Data Objectives: To find an equation of a line that models given data

Example 1 A plumber charges $51 for 2 hours of work and $74.25 for 3 ½ hours of work. Write an equation relating cost to number of hours worked. (2, 51) and (3.5, 74.25) m= y – y 1 = m(x – x 1 ) = 15.5 y – 51 = 15.5(x – 2) y – 51 = 15.5x – 31 y = 15.5x + 20

Example 2 Suppose the Island Club is selling greeting cards to raise money for a fundraiser. You estimate that you can sell 200 boxes of all-occasion cards and 300 boxes of birthday cards. Write an equation to find what prices you should set for the cards to raise $1000. Let a = the cost, per box, of all-occasion cards Let b = the cost, per box, of b-day cards 200a +300b= 1000

Practice Add or subtract.

Homework p.