SOLUTION: You need to buy a new refrigerator for your house. There are two models that you are comparing. A standard model cost $400 and uses $8 of electricity per month. An energy efficient

Question 1129307: You need to buy a new refrigerator for your house. There are two models that you are comparing. A standard model cost $400 and uses $8 of electricity per month. An energy efficient model cost $800 and uses $4 of electricity per month.
1. Write a linear equation that represents the total cost of the standard model of the refrigerator. Use C for the total cost and t for time measured in months.
2, Write a linear equation that represents the total cost of energy efficient model of the refrigerator. Use C for the total cost and t for time measured in months.
3. Label both axis and then graph the system of equations from questions 1 and 2. Indicate and label the solution to the system of equations on the graph.
4.Solve the linear system from questions 1 and 2 using the substitution method.
5. Solve the linear system from questions 1 and 3 using the elimination method.
6. In terms of these two refrigerators, what does the intersections of the lines in question 3 represent?
7. How are the solution in 3,4,and 5 related?why?
8. Which refrigerator would you buy? Justify your answer.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
1.C=400+8t
2.C=800+4t
3.
4. 400+8t=800+4t, substituting for C
4t=400
t=100 months
5.C=400+8t
-C=-800-4t
0=-400+4t
4t=400
t=100, C=1200
6.Intersection is the breakeven point.
7. The solutions are the same graphically, with substitution and elimination.
8. If one is going to have the refrigerator for more than 8 1/3 years, the more expensive one would be cheaper. If one were not going to have it for that long, the cheaper one would save money although it would use more electricity.
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