5.2+Breaking+Even

May 5 2009 CM

Big Idea: negative numbers help us to model many real world situations. Essential Question: How do i multiply and divide integers?

Notes from Class: look at any examples from the white board.

Any new vocabulary and definition(s): integer- The whole numbers and their opposites. 0 is an integer, but is neither positive nor negative. negative number- A number less than 0. positive number- A number greater than 0. opposites- two numbers whose sum is 0. For example. -3 and 3 are opposites. On a number line, opposites are the same distance from 0 but in different directions from 0. The number 0 is its own opposite.

Any examples from the white board:

A. Q:**Make a table that shows the profit Jean will earn for 0 through 20 tune-ups.** A: //P=(60 x t) - 800//

B. Q:**Plot the (tune-ups, profit) data from your table on a coordinate grid. Be sure to label the axes. Explain how you chose the scale for each axis.** A: //I chose the scale for the x axis because it would make more sense because the tune-ups went up by ones and the profit went up by 60. I decided to make the y axis more simple by going up by one hundreds.//

C. Q:**What will Jean's profit be if she does only four tune-ups? How is this shown on the graph?** A**:**//If Jean only does four tune-ups then her profit will be -560$. This is shown on the graph as (4,-560) in the fourth quadrant.//

D. Q: **How many tune-ups will Jean have to do before she breaks even? How is this shown on the graph?** A: //Jean will have to make 13 tune-ups before she starts making money. This is shown on the graph as (13,-20) in the fourth quadrant.//

E. Q: **How does Jean's profit change with each tune-up she does? How is this shown on the graph?** A: //Every tune-up Jean does earns her 60$. This is shown on the graph as a straight line starting in the fourth quadrant and ending in the first quadrant.//

follow-up: 1. Q:**What is the break even point for P=60t-600?** A: //11 tune-ups is the break even point for the profit equation, p=60t-600.//

2. Q:**What is the break even point for P=60t-1200?** A://21 tune-ups is the break even point for the profit equation, p= 60t-1200.//