document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1003154>Question 1003154</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A girl stands on the edge of her dorm roof and throws a ball into the air. The ball's height above the ground after t seconds is given by h = -16t^2+16t+320 When will the ball hit the ground? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #619940 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=619940\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> h = -16t^2+16t+320<BR>\n" );
document.write( "we want to solve the quadratic for t when h = 0<BR>\n" );
document.write( "-16t^2+16t+320 = 0<BR>\n" );
document.write( "divide both sides of = by -16<BR>\n" );
document.write( "t^2 -t - 20 = 0<BR>\n" );
document.write( "now factor the quadratic<BR>\n" );
document.write( "(t-5) * (t+4) = 0<BR>\n" );
document.write( "we get two solutions for t, that is t = 5 or -4<BR>\n" );
document.write( "we reject the -4 solution since time does not run backwards<BR>\n" );
document.write( "t = 5 seconds is the solution, <BR>\n" );
document.write( "the ball will hit the ground in 5 seconds<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );