3: Math 112 Written Homework: Linear Functions Student Name:____________________________________________ Instructor: J.M.S. Liston Math 112 Section:________ Directions: ANSWER THE FOLLOWING QUESTIONS ON YOUR OWN BLANK, WHITE PAPER (e.g. printer paper). Begin by first stating what you know, then what you're trying to find; be sure to SHOW ALL WORK to reflect your thinking and calculations. Explanations should be given in complete sentence (i.e., subject and verb). All graphs should be drawn accurately, SCALED, both axes identified with units. Staple this page to the TOP of your work. Be sure to put your name on all submitted pages. Failure to follow these instructions will result in a lower grade. 1. A solar water heater costs about $6240 to install (after rebates). A traditional gas water heater costs about $850, and costs about $320 per year to run. The average annual cost to run the solar water heater is about $75. Create total cost functions for each of the water heaters as a function of the number of years that it is used, and graph these functions on the same set of axes. How many years would you need to use a solar water heater in order for the total cost to become less than the total cost of the gas water heater? 2. Ricardo is paying off a $8640 loan by making equal payments over a 12-month period until the loan is paid. Express the amount of debt remaining as a function of time in months. What is the appropriate domain for this function? What is the slope of the function? What does the slope tell you in practical terms? Is this function increasing or decreasing? How do you know