Warm-Up6 minutes1) 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 Data7.7 Fitting Equations to Data7.7 Fitting Equations to Data7.7 Fitting Equations to DataObjectives: •To find an equation of a line that models given data

Example 1A 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=

74.25 513.5 2

23.251.5

y – y1 = m(x – x1)

= 15.5

y – 51 = 15.5(x – 2)

y – 51 = 15.5x – 31

y = 15.5x + 20

Example 2Suppose 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 cardsLet b = the cost, per box, of b-day cards

200a

+300b

= 1000

PracticeAdd or subtract.

Homework

p.