document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1208092>Question 1208092</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In the summer of 2009,Duke Energy supplied electricity to residences of Ohio for amonthly customer charge of $4.50 plus 4.2345¢ per kilowatt-hour (kWhr) for thefirst 1000 kWhr supplied in the month and 5.3622¢ per kWhr for all usage over 1000 kWhr in the month.\r<BR>\n" );
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document.write( "If C is the monthly charge for x kilowatt-hours, write a model relating charge and <BR>\n" );
document.write( "kilowatt-hours used. That is, write C as a function of x.\r<BR>\n" );
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document.write( "I know that our equation model begins with C(x) = something + something else in terms of x. \r<BR>\n" );
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document.write( "Here is what the textbook tells me.\r<BR>\n" );
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document.write( "The model can be found by multiplying x times $0.042345 and adding the montgly customer charge of $4.50.\r<BR>\n" );
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document.write( "The model is C(x) = $4.50 + x(0.042345).\r<BR>\n" );
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document.write( "Question:\r<BR>\n" );
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document.write( "Where did $0.042345 come from? <BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #846255 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52858)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=846255\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The solution in the post by @mananth is incomplete.\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The complete solution should be, &nbsp;OBVIOUSLY, &nbsp;a piecewise linear function  &nbsp;C(x)\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;with one formula for &nbsp;0 <= x <= 1000 &nbsp;kilowatts-hours and another formula for &nbsp;x > 1000 kilowatt-hours.\r<BR>\n" );
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document.write( "<PRE STYLE=\"white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;\">\r\n" );
document.write( "For 0 <= x <= 1000 kWh, the formula is\r\n" );
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document.write( "    C(x) = 4.50 + 0.042345x  dollars  (rounded to the closest cent).\r\n" );
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document.write( "At x = 1000 kWh, it gives  C(1000) = 4.50 + 0.042345*1000 = 46.845 dollars before rounding,\r\n" );
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document.write( "                                                       or = 46.85 dollars after rounding.\r\n" );
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document.write( "For x > 1000 kWh, the formula is\r\n" );
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document.write( "    C(x) = 46.85 + 0.053622*(x-1000)  dollars  (rounded to the closest cent).\r\n" );
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document.write( "It is a complete solution to the problem.\r\n" );
document.write( "</PRE>\r<BR>\n" );
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document.write( "Solved in full, &nbsp;with complete explanations.\r<BR>\n" );
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document.write( "When you ask where the coefficients come from, this is a completely childish <BR>\n" );
document.write( "question - it does not correspond to the level of the problem.\r<BR>\n" );
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document.write( "The level of the problem is about 9-th grade.\r<BR>\n" );
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document.write( "The level of the question \"where the coefficients come from\" is about 3-rd or 4-th grade.\r<BR>\n" );
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document.write( "So, you try to solve a problem of the 9-th grade without having solid base/knowledge of the 4-th grade.\r<BR>\n" );
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document.write( "It is what I see from your post.\r<BR>\n" );
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