document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1129307>Question 1129307</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 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. <BR>\n" );
document.write( "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.<BR>\n" );
document.write( "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.<BR>\n" );
document.write( "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.<BR>\n" );
document.write( "4.Solve the linear system from questions 1 and 2 using the substitution method.<BR>\n" );
document.write( "5. Solve the linear system from questions 1 and 3 using the elimination method.<BR>\n" );
document.write( "6. In terms of these two refrigerators, what does the intersections of the lines in question 3 represent?<BR>\n" );
document.write( "7. How are the solution in 3,4,and 5 related?why?<BR>\n" );
document.write( "8. Which refrigerator would you buy? Justify your answer. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #745868 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=745868\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 1.C=400+8t<BR>\n" );
document.write( "2.C=800+4t<BR>\n" );
document.write( "3.<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28300%2C300%2C-10%2C110%2C-100%2C1400%2C400%2B8x%2C800%2B4x%29 ALIGN=MIDDLE  ALT=\"graph%28300%2C300%2C-10%2C110%2C-100%2C1400%2C400%2B8x%2C800%2B4x%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "4. 400+8t=800+4t, substituting for C<BR>\n" );
document.write( "4t=400<BR>\n" );
document.write( "t=100 months<BR>\n" );
document.write( "5.C=400+8t<BR>\n" );
document.write( "-C=-800-4t<BR>\n" );
document.write( "0=-400+4t<BR>\n" );
document.write( "4t=400<BR>\n" );
document.write( "t=100, C=1200<BR>\n" );
document.write( "6.Intersection is the breakeven point.<BR>\n" );
document.write( "7.  The solutions are the same graphically, with substitution and elimination.<BR>\n" );
document.write( "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.  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );