document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=266702>Question 266702</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi everyone, I'm having a bit of a problem with, well, a problem.  We've been dealing with quadratic equations and I'm pretty sure that's how to solve the problem, however I can't figure out how to set up the problem.\r<BR>\n" );
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document.write( "Here's the posed problem:\r<BR>\n" );
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document.write( "In March of 2000, Doug Danger made a sucessful motorcycle jump over an L-1011 jumbo jet.  The horizontal distance of his jump was 160 feet, and his height, in feet, during the jump was approximated by h = -16t^2 + 25.3t + 20, t>/=0.<BR>\n" );
document.write( "He left the takeoff ramp at a height of 20 feet and he landed on the landing ramp at a height of about 17 feet.  How long, to the nearest 10th of a second, was he in the air.\r<BR>\n" );
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document.write( "Now I did attempt to solve for T by setting h to zero and h to 17.<BR>\n" );
document.write( "Setting h to zero gave me -25.3 +/- sqrt (25.3^2-4(-16)(20)/2(-16) = -25.3 +/- sqrt 1920.09/-32<BR>\n" );
document.write( "Setting h to 17 = -25.3 +/- sqrt 448.09/-32\r<BR>\n" );
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document.write( "I'm obviously missing something, but what? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #195939 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><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=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=195939\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> \"He left the takeoff ramp at a height of 20 feet and he landed on the landing ramp at a height of about 17 feet\"\r<BR>\n" );
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document.write( "he takes off at time zero ___ this is why h=20 when t=0\r<BR>\n" );
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document.write( "solving for t when h=17 gives the flight time<BR>\n" );
document.write( "___ there is also a negative t solution for h=17 ___ this roughly corresponds to time BEFORE takeoff, when he is going up the ramp\r<BR>\n" );
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document.write( "17 = -16t^2 + 25.3t + 20 ___ 0 = -16t^2 + 25.3t + 3 ___ b^2 - 4ac = 832.09\r<BR>\n" );
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document.write( "using quadratic formula ___ t = -.11 and  t = 1.69 ___ 1.7 to the nearest tenth\r<BR>\n" );
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document.write( "\"I'm obviously missing something, but what?\"<BR>\n" );
document.write( "___ it looks like the sign is reversed in the b^2 - 4ac of your calculation for h=17 </SPAN>\n" );
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