document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=281657>Question 281657</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A ball falls off the top of a roof 320 feet above the ground.  The formula h= -16t^2 + 16t +320 describes the height of the ball above the ground, h, in feet, t seconds after the fall begins.  How long will it take the ball to strike 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 #204675 by </B><A HREF=/tutors/aboutme.mpl?userid=Greenfinch><B>Greenfinch(383)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Greenfinch><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=Greenfinch><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=204675\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Ball hits ground when h = 0<BR>\n" );
document.write( "So equation becomes 0= -16t^2 + 16t +320<BR>\n" );
document.write( "Divide by -16 to get  t^2 - t - 20 = 0<BR>\n" );
document.write( "So (t-5)(t + 4)=0<BR>\n" );
document.write( "t = 5 or -4 seconds<BR>\n" );
document.write( "So t = 5  </SPAN>\n" );
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