Lesson 12

“When will we ever use this?”

is a question math teachers tend to hear when math concepts tend to be more abstract.  My favorite answer I would give my students was that they will be using it TODAY.  J   Graphing linear, quadratic, cubic, and other types of equations are topics that tend to increase the probability that the question, “When will we ever use this?” will be heard.  However, graphs are incredible tools to visually convey a lot of information in a small amount of space.

DJ CostThis course will only focus on linear graphs.  Examine the graph to the right.  The graph shows the fees that two different deejay companies charge.  Both Little Jimmy’s DJ Service and Big Bob’s DJ Service have great rates; however, when would it be advantageous of you to use each company?  Both companies’ fees are displayed as a line.  This means that their rates are constant for each hour they work.  One company charges less than the other for their onetime charge.  Which one is that?  (Little Jimmy’s = $100)  Which company would be less expensive for a 5 hour party?  (Big Bob’s = $425)  Which company charges more per hour?  (Little Jimmy’s)  How can you tell?  (The line is steeper.)  Although in this lesson we are going to graph lines, they won’t be in context, meaning, they won’t be representing a specific situation.  But I just want you to know that you could really use graphs of linear equations not only in this class but in your life outside this class.

Here is an additional tutorial to watch to help you with how to find ordered pairs for an equation, how to graph an equation and how to calculate slope.  You will need coordinate graph paper for a group of problems on Exercise 4.2 Parts A, B, & C.   You can download coordinate graph paper here:  Multiple_Coordinate_Graphs_4-per-Page 

If you need additional practice beyond what is in the textbook, print off the following worksheets & answer keys: Graph Lines from a Table Extra Practice WorksheetGraph Lines from an Equation Extra Practice Worksheet and Slope Extra Practice Worksheet.