document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=187380>Question 187380</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a ball is thrown into the air in such a way that its distance(d), in feet, above the ground at any time(t), in seconds, is given by the equation d=40t-5t^2.\r<BR>\n" );
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document.write( "how many seconds will it take for the ball to reach a height of 80ft above 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 #140496 by </B><A HREF=/tutors/aboutme.mpl?userid=checkley77><B>checkley77(12844)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=checkley77><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=140496\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> d=40t-5t^2.<BR>\n" );
document.write( "80=40T-5T^2<BR>\n" );
document.write( "5T^2-40T+80=0<BR>\n" );
document.write( "5(T^2-8T+16)=0<BR>\n" );
document.write( "5(T-4)(T-4)=0<BR>\n" );
document.write( "T-4=0<BR>\n" );
document.write( "T=4 SEC. ANS.<BR>\n" );
document.write( "PROOF:<BR>\n" );
document.write( "80=40*4-5*4^2<BR>\n" );
document.write( "80=160-5*8<BR>\n" );
document.write( "80=160-80<BR>\n" );
document.write( "80=80 </SPAN>\n" );
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