document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=113519>Question 113519</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An object is projected upward from the top of a tower.  Its distance in feet above the ground after t seconds is given by s(t)=-16t+64t+80.  How many seconds will it take to reach ground level? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #82592 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=82592\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> An object is projected upward from the top of a tower.  Its distance in feet above the ground after t seconds is given by s(t)=-16t^2+64t+80.  How many seconds will it take to reach ground level?<BR>\n" );
document.write( "-------------------<BR>\n" );
document.write( "When it reaches the ground s(t)=zero.<BR>\n" );
document.write( "Solve -16t^2+64t+80=0<BR>\n" );
document.write( "-16(t^2-4t-5)=0<BR>\n" );
document.write( "(t-5)(t+1)=0<BR>\n" );
document.write( "t=5 seconds or t=-1 second<BR>\n" );
document.write( "Only t=5 seconds makes any sense for this problem.<BR>\n" );
document.write( "=============<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );