document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1034820>Question 1034820</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Benjamin threw a rock straight up from a cliff that was 48 ft above the water. If the height of the rock h, in feet, after t seconds is given by the equation h=-16t^2+52t+48, how long will it take for the rock to hit the water?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #649494 by </B><A HREF=/tutors/aboutme.mpl?userid=fractalier><B>fractalier(6550)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=fractalier><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=fractalier><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=649494\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> For h(t) = -16t^2 + 52t + 48, which is the height of the rock as a function of time, we want to know at what time the height equals zero.  So we set it equal to zero and solve for t...<BR>\n" );
document.write( "-16t^2 + 52t + 48 = 0  (now divide by -4)<BR>\n" );
document.write( "4t^2 - 13t - 12 = 0<BR>\n" );
document.write( "which is factorable into<BR>\n" );
document.write( "(4t + 3)(t - 4) = 0<BR>\n" );
document.write( "so that<BR>\n" );
document.write( "t = 4 seconds </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );