2x + 8 = 32 6x - 6 = 12 a) x = 12 b) x = 3 21 = 2x x – 30 = 100 c) x = 7.5 d) x = 13

 Learning Target: I can solve, check, and graph systems of equations and find the intersection point  Language Objective: I can explain how to solve and check systems of equations. I can explain what the point of intersection means.  Technology Objective: I can use the internet and/or graphing calculator to solve, check, and evaluate systems of equations.

 Tanks-A-Lot  y = 3x  Teesers  y = 5x + 78  Sreeners  y = 7x + 50

Complete the chart for total cost.  Tanks-A-Lot  y = 7x + 50  Teesers  y = 5x + 78  Sreeners  y = 7x + 50

Graph the systems of equations using the resource page provided. Make sure to complete graph & identify each vendor in a different color.

 MC Tanks-A-Lot Teesers Screeners

1. Go to: Algebra, 6-8 th, grapher. 2. Adjust the window screen to match your hand graphed x-and y-axis. 3. Functions tab f(x), g(x), h(x): enter the equation for each company: Tanks-A-Lot, Teesers, and Screeners. 3. Evaluate the “graph” each equation and compare to your hand graph. 4. Use the “trace” mode to identify the point of intersection. Compare the “traced” point to your hand graph.

1. Adjust the window screen to match your hand graphed x-and y-axis. 2. Using the y = mode, enter the equation for each company: Tanks-A-Lot, Teesers, and Screeners. 3. Now “graph” each equation and compare to your hand graph. 4. Use the “trace” mode to identify the point of intersection. Compare the “traced” point to your hand graph.

a) If she buys 5 shirts, cost for each vendor is: b) If she buys 15 shirts, cost for each vendor is: c) If she buys 45 shirts, cost for each vendor is: For each option above, identify which vendor is the most economical choice.

a) If she buys 5 shirts, cost for each vendor is: Tanks-A-Lots = $135, Teeser = $103, Screeners = $85; Screeners will be more economical. b) If she buys 15 shirts, cost for each vendor is: Tanks-A-Lots = $165, Teeser = $153, Screeners = $155; Teesers will be more economical. c) If she buys 45 shirts, cost for each vendor is: Tanks-A-Lots = $255, Teeser = $303, Screeners = $365; Tanks-A-Lot will be more economical. Use the graphs to help Diedre decide which company she should select, depending on the size of the order.

Identify the point of intersection of Teesers and Tanks-A-Lot. What does this point mean? Write and solve one equation for Teesers and Tanks-A-Lot to show at what point the two vendors’ cost is the same. Compare your calculated answer with your graph. Write and solve one equation for Teesers and Screeners to show at what point the two vendors’ cost is the same. Compare your calculated answer with your graph. Identify the point of intersection for Teesers and Screeners. What does this point mean?

Identify the point of intersection of Teesers and Tanks- A-Lot. What does this point mean? The lines cross at (21, 183) that means both companies will sell her 21 shirts for $183. Write and solve one equation for Teesers and Tanks-A- Lot to show at what point the two vendors’ cost is the same. Compare your calculated answer with your graph. The results are the same for 21 shirts it will cost $183 at both companies. Write and solve one equation for Teesers and Screeners to show at what point the two vendors’ cost is the same. Compare your calculated answer with your graph. The results are 14 shirts will cost $148 at both companies. Identify the point of intersection for Teesers and Screeners. What does this point mean? The lines cross at (14, 148) that means both companies will sell her 14 shirts for $148.