document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=599430>Question 599430</A>: <I><SPAN STYLE=\"word-break: break-all;\">  A video store sells about 100 DVDs a week at a price of $21 each. The owner estimates that for each $3 decrease in price, about 20 more DVDs will be sold each week. How can the owner maximize weekly revenue? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #378971 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=378971\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+ ALIGN=MIDDLE  ALT=\"+x+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the number of $3 decreases in price<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+ ALIGN=MIDDLE  ALT=\"+R+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = weekly revenue<BR>\n" );
document.write( "given:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+%28+21+-+3x+%29%2A%28+100+%2B+20x+%29+ ALIGN=MIDDLE  ALT=\"+R+=+%28+21+-+3x+%29%2A%28+100+%2B+20x+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+2100+-+300x+%2B+420x+-+60x%5E2+ ALIGN=MIDDLE  ALT=\"+R+=+2100+-+300x+%2B+420x+-+60x%5E2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+-60x%5E2+%2B+120x+%2B+2100+ ALIGN=MIDDLE  ALT=\"+R+=+-60x%5E2+%2B+120x+%2B+2100+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%2F60+=+-x%5E2+%2B+2x+%2B+35+ ALIGN=MIDDLE  ALT=\"+R%2F60+=+-x%5E2+%2B+2x+%2B+35+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "This parabola has a maximum since the<BR>\n" );
document.write( "coefficient of the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E2 ALIGN=MIDDLE  ALT=\"x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > term is minus<BR>\n" );
document.write( "The maximum is at <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=++-b%2F%282a%29+ ALIGN=MIDDLE  ALT=\"x+=++-b%2F%282a%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > when<BR>\n" );
document.write( "the equation has the form<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+ax%5E2+%2B+b%2Ax+%2B+c+ ALIGN=MIDDLE  ALT=\"+ax%5E2+%2B+b%2Ax+%2B+c+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+=+-1+ ALIGN=MIDDLE  ALT=\"+a+=+-1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+=+2+ ALIGN=MIDDLE  ALT=\"+b+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-b%2F%282a%29+=+-2%2F%282%2A%28-1%29%29+ ALIGN=MIDDLE  ALT=\"+-b%2F%282a%29+=+-2%2F%282%2A%28-1%29%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-b%2F%282a%29+=+1+ ALIGN=MIDDLE  ALT=\"+-b%2F%282a%29+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "When <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+1+ ALIGN=MIDDLE  ALT=\"+x+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" >, <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%2F60+=+-%281%29%5E2+%2B+2%2A1+%2B+35+ ALIGN=MIDDLE  ALT=\"+R%2F60+=+-%281%29%5E2+%2B+2%2A1+%2B+35+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%2F60+=+-1+%2B+2+%2B+35+ ALIGN=MIDDLE  ALT=\"+R%2F60+=+-1+%2B+2+%2B+35+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%2F60+=+36+ ALIGN=MIDDLE  ALT=\"+R%2F60+=+36+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+2160+ ALIGN=MIDDLE  ALT=\"+R+=+2160+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The owner can maximize revenue by<BR>\n" );
document.write( "decreasing the price once by $3/CD<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+0+ ALIGN=MIDDLE  ALT=\"+x+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+%28+21+-+3%2A0+%29%2A%28+100+%2B+20%2A0+%29+ ALIGN=MIDDLE  ALT=\"+R+=+%28+21+-+3%2A0+%29%2A%28+100+%2B+20%2A0+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+2100+ ALIGN=MIDDLE  ALT=\"+R+=+2100+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-------------<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+1+ ALIGN=MIDDLE  ALT=\"+x+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+%28+21+-+3%2A1+%29%2A%28+100+%2B+20%2A1+%29+ ALIGN=MIDDLE  ALT=\"+R+=+%28+21+-+3%2A1+%29%2A%28+100+%2B+20%2A1+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+18%2A120+ ALIGN=MIDDLE  ALT=\"+R+=+18%2A120+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+2160+ ALIGN=MIDDLE  ALT=\"+R+=+2160+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-------------<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+2+ ALIGN=MIDDLE  ALT=\"+x+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+%28+21+-+3%2A2+%29%2A%28+100+%2B+20%2A2+%29+ ALIGN=MIDDLE  ALT=\"+R+=+%28+21+-+3%2A2+%29%2A%28+100+%2B+20%2A2+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+15%2A140+ ALIGN=MIDDLE  ALT=\"+R+=+15%2A140+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R+=+2100+ ALIGN=MIDDLE  ALT=\"+R+=+2100+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "   </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );