document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1028630>Question 1028630</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A football is kicked into the air. The height of the football is modelled by h(t)=-5t^2+16t+1 when the height is in metres and t is the time in seconds from its release. When will the football first reach the height of 13 metres? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #643719 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=643719\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> You are given that <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+h%28t%29+=+13+ ALIGN=MIDDLE  ALT=\"+h%28t%29+=+13+\"   DISABLED_style= \"max-width:90%; height:auto;\" > where<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+h%28t%29+=+-5t%5E2+%2B+16t+%2B+1+ ALIGN=MIDDLE  ALT=\"+h%28t%29+=+-5t%5E2+%2B+16t+%2B+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-5t%5E2+%2B+16t+%2B+1+=+13+ ALIGN=MIDDLE  ALT=\"+-5t%5E2+%2B+16t+%2B+1+=+13+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-5t%5E2+%2B+16t+-+12+=+0+ ALIGN=MIDDLE  ALT=\"+-5t%5E2+%2B+16t+-+12+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Use quadratic formula<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%28+-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28+-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+=+-5+ ALIGN=MIDDLE  ALT=\"+a+=+-5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+=+16+ ALIGN=MIDDLE  ALT=\"+b+=+16+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+=+-12+ ALIGN=MIDDLE  ALT=\"+c+=+-12+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%28+-16+%2B-+sqrt%28+16%5E2+-+4%2A%28-5%29%2A%28-12%29+%29%29+%2F+%282%2A%28-5%29+%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28+-16+%2B-+sqrt%28+16%5E2+-+4%2A%28-5%29%2A%28-12%29+%29%29+%2F+%282%2A%28-5%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=+t+=+%28+-16+%2B-+sqrt%28+256+-+240+%29%29+%2F+%28-10+%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28+-16+%2B-+sqrt%28+256+-+240+%29%29+%2F+%28-10+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%28+-16+%2B-+sqrt%28+16+%29%29+%2F+%28-10+%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28+-16+%2B-+sqrt%28+16+%29%29+%2F+%28-10+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%28+-16+%2B+4+%29+%2F+%28-10%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28+-16+%2B+4+%29+%2F+%28-10%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%28-12%29%2F%28-10%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28-12%29%2F%28-10%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+1.2+ ALIGN=MIDDLE  ALT=\"+t+=+1.2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and also<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%28+-16+-+4+%29+%2F+%28-10%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28+-16+-+4+%29+%2F+%28-10%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+%28-20%29%2F%28-10%29+ ALIGN=MIDDLE  ALT=\"+t+=+%28-20%29%2F%28-10%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+2+ ALIGN=MIDDLE  ALT=\"+t+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "----------<BR>\n" );
document.write( "The first time the height of the ball is at 13 m<BR>\n" );
document.write( "is 1.2 sec<BR>\n" );
document.write( "-------------<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "Here's the plot:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+graph%28+600%2C+600%2C+-2%2C+4%2C+-2%2C+15%2C+-5x%5E2+%2B+16x+%2B+1+%29+ ALIGN=MIDDLE  ALT=\"+graph%28+600%2C+600%2C+-2%2C+4%2C+-2%2C+15%2C+-5x%5E2+%2B+16x+%2B+1+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );