document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1051603>Question 1051603</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An emergency flare is launched from platform and its height h in metres after t seconds is given by the equation h =-4.9t^2 + 78.4t + 11.3\r<BR>\n" );
document.write( "\n" );
document.write( "a)What is the maximum height of the flare?\r<BR>\n" );
document.write( "\n" );
document.write( "b) after how many seconds does the flare reach the maximum height?\r<BR>\n" );
document.write( "\n" );
document.write( "c) when will the flare hit the ground below?\r<BR>\n" );
document.write( "\n" );
document.write( "d) determine the height of the platform\r<BR>\n" );
document.write( "\n" );
document.write( "My attempt<BR>\n" );
document.write( "a) -4.4(x-8)^2+324.9\r<BR>\n" );
document.write( "\n" );
document.write( "b) 11.3 seconds </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #667073 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=667073\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> h =-4.9t^2 + 78.4t + 11.3 <BR>\n" );
document.write( "h = -4.9(t-8)^2 + 4.9(64) + 11.3<BR>\n" );
document.write( "h = -4.9(t-8)^2 + 313.6 + 11.3<BR>\n" );
document.write( "h = -4.9(t-8)^2 + 324.9  Good Work<BR>\n" );
document.write( "Parabola opening downward V(8, 324.9)<BR>\n" );
document.write( "a) maximum height = 324.9m<BR>\n" );
document.write( "b) after how many seconds does the flare reach the maximum height: t = 8sec<BR>\n" );
document.write( "c) when will the flare hit the ground below? h = 0<BR>\n" );
document.write( "0 =-4.9(t-8)^2 + 324.9 <BR>\n" );
document.write( "4.9(t-8)^2 = 324.9<BR>\n" );
document.write( "(t-8)^2 = 324.9/4.9<BR>\n" );
document.write( "t = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%28324.9%2F4.9%29+%2B+8+ ALIGN=MIDDLE  ALT=\"sqrt%28324.9%2F4.9%29+%2B+8+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "d) determine the height of the platform: <BR>\n" );
document.write( "h =-4.9t^2 + 78.4t + 11.3 <BR>\n" );
document.write( "t = 0, the height of the platform is 11.3m </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );