document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=255988>Question 255988</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The owner of an apartment building with 50 units has found that if the rent for each unit is $360 per month, all the units will be filled.  He wants to increase the rent but has calculated that one unit will become vacant for each $10 increase in monthly rent. What monthly rent would maximize the monthly income for the owner? What is his maximum monthly income.\r<BR>\n" );
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document.write( "I'm pretty sure the equation is y=-10x^2+140x+18000.<BR>\n" );
document.write( "Then I did the (-b/2a) and got 7...what do I do after that? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #188195 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=188195\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> if you right, they you want to find f(-b/2a)\r<BR>\n" );
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document.write( "take the value of 7 and plug it into the equation to get:\r<BR>\n" );
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document.write( "y=-10x^2+140x+18000 becomes:\r<BR>\n" );
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document.write( "y=-10(7)^2+140(7)+18000 becomes:\r<BR>\n" );
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document.write( "y = -490 + 980 + 18000 = 18490 which should be the maximum rent he collects for the month.\r<BR>\n" );
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document.write( "graph of your equation looks like:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph+%28600%2C600%2C-10%2C75%2C-5000%2C25000%2C-10%2Ax%5E2+%2B+140%2Ax+%2B+18000%29 ALIGN=MIDDLE  ALT=\"graph+%28600%2C600%2C-10%2C75%2C-5000%2C25000%2C-10%2Ax%5E2+%2B+140%2Ax+%2B+18000%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "y looks like it represents the total rent for the month.\r<BR>\n" );
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document.write( "x looks like it represents the number of units vacant for the month.\r<BR>\n" );
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document.write( "based on that the graph looks good.\r<BR>\n" );
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document.write( "7 vacant rooms means 43 filled at 360 + 70 = 430 per room = 18490.<BR>\n" );
document.write( "6 vacant rooms means 44 filled at 360 + 60 = 420 per room = 18480.<BR>\n" );
document.write( "8 vacant rooms means 42 filled at 360 + 80 = 440 per room = 18480.\r<BR>\n" );
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document.write( "you definitely get peak revenue with 7 vacant rooms.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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