document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=57318>Question 57318</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please help me.\r<BR>\n" );
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document.write( " A ball is thrown upwards from the roof of a buildiung 100 m tall with an inituial velocity of 20m/s.  When will the ball reach a height of 80m?<BR>\n" );
document.write( "I believe the equation is h=5t^2+80t+100.  How do I solve using quadratic formula?\r<BR>\n" );
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document.write( "Thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #39048 by </B><A HREF=/tutors/aboutme.mpl?userid=Nate><B>Nate(3500)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Nate><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=39048\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> f(x) = -16t^2 + 20t + 100<BR>\n" );
document.write( "~> Ball reaches 80m.<BR>\n" );
document.write( "80 = -16t^2 + 20t + 100<BR>\n" );
document.write( "-20 = -16t^2 + 20t<BR>\n" );
document.write( "5/4 = t^2 - 5t/4<BR>\n" );
document.write( "105/4 = 80/64 + 25/64 = (t - 5/8)^2<BR>\n" );
document.write( "+-sqrt(105)/2 = t - 5/8<BR>\n" );
document.write( "5/8 +- 4*sqrt(105)/8 = t </SPAN>\n" );
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