compare two cell phone companies offers to see which is the better deal.
Horizon Cell Phone Company
Vertigo Cell Phone Company
Plus every minute costs $0.05
Plus every minute costs $0.07
Step 1: Write a linear equation of the form y1=mx+b for the Horizon Cell Phone Company. Graph this equation on the xy-plane and label it as y1. Be sure to include a large enough set of x-values (something like [0,800] would be suitable. Graphing values only from [0,10] would not yield very much information, since most cell phone users talk for more than 10 minutes each month. Also, be sure to include a title on the graph and labels on the x- and y-axes.
Step 2: Write a linear equation of the form y2=mx+b for the Vertigo Cell Phone Company. Graph this equation on the same graph. You will now have two lines on the same graph. These should intersect.
Step 3: Find the point of intersection for y1 and y2 algebraically. Show your work and also plot this point on the graph.
Step 4: Analyze which company offers a cheaper deal on cell phone costs and under what conditions. At what value are they the same?
Step 5: Suppose you talk an average of 200 minutes per month. Which is your best option? What is the difference in price between the two companies' charges for 200 minutes.