document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1083628>Question 1083628</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose a model rocket is launched from a platform 2 ft above the ground with an initial upward velocity of 150 ft/s. How long will it take the rocket to 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 #697681 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=697681\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The equation is f(t)=-16t^2+150t+2<BR>\n" );
document.write( "It hits the ground when f(t)=0<BR>\n" );
document.write( "factor out a -2 and divide both sides by it.<BR>\n" );
document.write( "8t^2-75t-1=0<BR>\n" );
document.write( "t=(1/16)(75+/- sqrt (5625+32);sqrt 5657=75.21<BR>\n" );
document.write( "use positive root only t=150.21/16=9.4 sec<BR>\n" );
document.write( "Check  by finding vertex t value which should be close (started +2 feet, so won't be exact) to half the entire time, since the vertex is the axis of symmetry.<BR>\n" );
document.write( "t=-b/2a at vertex=-150/-32=4.7 sec.<BR>\n" );
document.write( "Check again by graphing.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28300%2C300%2C-10%2C15%2C-20%2C400%2C-16x%5E2%2B150x%2B2%29 ALIGN=MIDDLE  ALT=\"graph%28300%2C300%2C-10%2C15%2C-20%2C400%2C-16x%5E2%2B150x%2B2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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