Quick Start Expectations1. Fill in planner and HWRS

HW: None! 2. Get a signature on HWRS3. On desk: journal, calculator, HWRS, pencil, pen

4. Warm Up: Analyze the table on the next slide

Warm-up

X Y

-2 1

0 5

3 11

5 15

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 = 2b = 5

y = 2x +5

Mightyy = 49 + x or y = x + 49

b = $49 initial feem = $1 cost per shirt

No-Shrinky = 4.5 x or y = 4.5x + 0

b = $0 initial feem = $4.50 cost per shirt

Mightyy = 49 + x or y = x + 49

x = 20

y = 49 + 20 = $69

No-Shrinky = 4.5 x or y = 4.5x + 0

x = 20

y = 4.5 x 20 = $90

Mightyy = 49 + x or y = x + 49

y = 120

120 = 49 + x120 – 49 = x x = 71 t-shirts

No-Shrinky = 4.5 x or y = 4.5x + 0

y = 120

120 = 4.5x 120/4.5 = x

x is about 26 t-shirts

Week (x) 0 5 10 15 14MightyCost (y)

$49 $54 $59 $64 $63

No- ShrinkCost (y)

$0 $22.50 $45 $67.50

$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!

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 $1No-Shrink Tee: as n increases by 1, the cost increases by $4.50

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.

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.

C = 34 + 2.50n