document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=967155>Question 967155</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A food truck sells 500 sandwiches per day when they charge $9 per sandwich. It sells 100 more sandwiches per day for each $1 decrease in price. What price should the vendor charge to maximize the profit? What would be the maximum profit?\r<BR>\n" );
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document.write( "My Work:\r<BR>\n" );
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document.write( "let x = number of money decrease<BR>\n" );
document.write( "let y = profit\r<BR>\n" );
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document.write( "y=500+9x<BR>\n" );
document.write( "y=9-1x\r<BR>\n" );
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document.write( "y=(500+9x)(9-x)<BR>\n" );
document.write( "y=4500-9x^2-500x+81x<BR>\n" );
document.write( "y=(-9x^2)-419x+4500\r<BR>\n" );
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document.write( "I tried to solve using quadratic formula but my answer was way too large of a number. What did I do wrong? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #591107 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39617)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=591107\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Your first equation is wrong.  Profit means revenue minus cost.\r<BR>\n" );
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document.write( "First, try to examine revenue and cost, either separately or together.<BR>\n" );
document.write( "Examining your description further, you have no way to know about profit because you have no cost information.\r<BR>\n" );
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document.write( "x, Money Decrease________Price_________count__________Revnu_________<BR>\n" );
document.write( "0________________________9_____________500<BR>\n" );
document.write( "1________________________8_____________500+1*100<BR>\n" );
document.write( "2________________________7___________500+2*100<BR>\n" );
document.write( "3______________________9-3___________500+3*100<BR>\n" );
document.write( "x______________________9-x___________500+100x_______(9-x)(500+100x)\r<BR>\n" );
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document.write( "You have now the function for revenue, using input, independant variable, x, the number of dollar decrease from $9.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28R%28x%29=%289-x%29%28500%2B100x%29%29 ALIGN=MIDDLE  ALT=\"highlight%28R%28x%29=%289-x%29%28500%2B100x%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Further factoring would be useful:<BR>\n" );
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document.write( "you should be able to find the roots and know how to handle the rest of the solution.  Recall, this is only for revenue because your problem description gives nothing about cost. </SPAN>\n" );
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