document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1195857>Question 1195857</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A stone was thrown from the top of a cliff 60 meters above sea level. The height of the<BR>\n" );
document.write( "stone above sea level t seconds after it was released, is given by H(t) = -5t2 + 20t + 60<BR>\n" );
document.write( "meters.<BR>\n" );
document.write( "a) Find the time it takes for the stone to reach its maximum height.<BR>\n" );
document.write( "b) Find the maximum height above sea level reached by the stone.<BR>\n" );
document.write( "c) How long did it take before the stone struck 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 #828441 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=828441\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A stone was thrown from the top of a cliff 60 meters above sea level. The height of the stone above sea level t seconds after it was released, is given by H(t) = -5t^2 + 20t + 60 meters.<BR>\n" );
document.write( "---<BR>\n" );
document.write( "a) Find the time it takes for the stone to reach its maximum height.<BR>\n" );
document.write( "The max of the quadratic is at t = -b/2a<BR>\n" );
document.write( "t = -20/-10 = 2 seconds<BR>\n" );
document.write( "--------<BR>\n" );
document.write( "b) Find the maximum height above sea level reached by the stone.<BR>\n" );
document.write( "H(2) = -5*4 + 20*2 + 60 = 80 meters<BR>\n" );
document.write( "----<BR>\n" );
document.write( "c) How long did it take before the stone struck the water?<BR>\n" );
document.write( "--- Poorly worded question.<BR>\n" );
document.write( "How many seconds passed from launch to impact?<BR>\n" );
document.write( "H(t) = -5t^2 + 20t + 60 = 0<BR>\n" );
document.write( "t^2 - 4t - 12 = 0<BR>\n" );
document.write( "(t-6)*(t+2) = 0<BR>\n" );
document.write( "t = 6 seconds to impact --- ignore the negative solution<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );