1. Quick Start Expectations 1.Fill in planner and HWRS HW: None! 2.Get a signature on HWRS 3.On desk: journal, calculator, HWRS, pencil, pen 4.Warm Up: Analyze the table on the next slide

2. Warm-up XY -21 05 311 515 Is this a linear relationship? If so, find the slope, y-intercept, and write the equation. If not, explain why it is not linear. Yes, this is a linear relationship. As x goes up by 1, y goes up by 2. m = 2 b = 5 y = 2x +5

11. Mighty y = 49 + x or y = x + 49 b = $49 initial fee m = $1 cost per shirt Mighty y = 49 + x or y = x + 49 b = $49 initial fee m = $1 cost per shirt No-Shrink y = 4.5 x or y = 4.5x + 0 b = $0 initial fee m = $4.50 cost per shirt No-Shrink y = 4.5 x or y = 4.5x + 0 b = $0 initial fee m = $4.50 cost per shirt

12. Mighty y = 49 + x or y = x + 49 x = 20 y = 49 + 20 = $69 Mighty y = 49 + x or y = x + 49 x = 20 y = 49 + 20 = $69 No-Shrink y = 4.5 x or y = 4.5x + 0 x = 20 y = 4.5 x 20 = $90 No-Shrink y = 4.5 x or y = 4.5x + 0 x = 20 y = 4.5 x 20 = $90

13. Mighty y = 49 + x or y = x + 49 y = 120 120 = 49 + x 120 – 49 = x x = 71 t-shirts Mighty y = 49 + x or y = x + 49 y = 120 120 = 49 + x 120 – 49 = x x = 71 t-shirts No-Shrink y = 4.5 x or y = 4.5x + 0 y = 120 120 = 4.5x 120/4.5 = x x is about 26 t-shirts No-Shrink y = 4.5 x or y = 4.5x + 0 y = 120 120 = 4.5x 120/4.5 = x x is about 26 t-shirts

14. Week (x) 05101514 Mighty Cost (y) $49$54$59$64$63 No- Shrink Cost (y) $0$22.50$45$67.5 0 $63 What is the vocabulary word for when the costs are equal? The break-even point or the point of intersection! If I need to buy more than 14 shirts, Mighty is the better deal. If I need to buy less than 14 shirts, No-Shrink is the better deal. Make a Table!

15. It is a linear relationship because each company is charging the same rate per t-shirt. Mighty charges $1 per shirt and No- Shrink charges $4.50 per shirt. Mighty Tee: as n increases by 1, the cost increases by $1 No-Shrink Tee: as n increases by 1, the cost increases by $4.50 Mighty Tee: as n increases by 1, the cost increases by $1 No-Shrink Tee: as n increases by 1, the cost increases by $4.50

16. The cost per T-shirt for this company is $2.50. The down payment, for no shirts, is $34. This cost is less per T-shirt than No-Shrink, but greater than Mighty. Yes, it is a linear relationship! As the number of t-shirts increases by 1, the cost increases by $2.50.

17. Yes, (20, 84) lies on this graph. If you extend the table to n = 20, then C = $84. Or you can substitute the x and y into the equation! The 20 means that if you buy 20 T-shirts it will cost $84. You can substitute the coordinates into the equation to make a true statement.

18. C = 34 + 2.50n