document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=130299>Question 130299</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Looking at <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=f%28x%29=-0.2x%5E2%2B12x%2B11 ALIGN=MIDDLE  ALT=\"f%28x%29=-0.2x%5E2%2B12x%2B11\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "After how many days will the peak or low occur?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #95160 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=95160\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The peak corresponds to the vertex of the parabola. So let's find the x-coordinate of the vertex\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "In order to do that,  we can use this formula:\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<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;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "From the equation <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=-0.2x%5E2%2B12x%2B11. ALIGN=MIDDLE  ALT=\"y=-0.2x%5E2%2B12x%2B11.\"   DISABLED_style= \"max-width:90%; height:auto;\" > we can see that a=-0.2 and b=12\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=%28-12%29%2F%282%2A%28-0.2%29%29 ALIGN=MIDDLE  ALT=\"x=%28-12%29%2F%282%2A%28-0.2%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > Plug in b=12 and a=-0.2\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=%28-12%29%2F%28-0.4%29 ALIGN=MIDDLE  ALT=\"x=%28-12%29%2F%28-0.4%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > Multiply 2 and -0.2 to get -0.4\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=30 ALIGN=MIDDLE  ALT=\"x=30\"   DISABLED_style= \"max-width:90%; height:auto;\" > Divide\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So the x-coordinate of the vertex is  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=30 ALIGN=MIDDLE  ALT=\"x=30\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So at the x-coordinate of the vertex, the peak will occur. So on the 30th day, the peak in ticket sales will occur. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );