document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1030331>Question 1030331</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown upward with an initial velocity of 80 feet per second from the edge of a cliff that is 384 feet above a river.  Use the function \r<BR>\n" );
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document.write( "a) How long will it take for the ball to land in the river?\r<BR>\n" );
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document.write( "b)  When is the ball 480 feet above the river?<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #645203 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=645203\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown upward with an initial velocity of 80 feet per second from the edge of a cliff that is 384 feet above a river.<BR>\n" );
document.write( " Use the function: h(t) = -16t^2 + 80t + 384<BR>\n" );
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document.write( "a) How long will it take for the ball to land in the river?<BR>\n" );
document.write( "The river is h(t) = 0<BR>\n" );
document.write( "-16t^2 + 80t + 384 = 0<BR>\n" );
document.write( "Simplify, divide equation by -16<BR>\n" );
document.write( "t^2 - 5t - 24 = 0<BR>\n" );
document.write( "Factors to<BR>\n" );
document.write( "(t-8)(t+3) = 0<BR>\n" );
document.write( "positive solution<BR>\n" );
document.write( "t = 8 seconds to land in the river<BR>\n" );
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document.write( "b) When is the ball 480 feet above the river?<BR>\n" );
document.write( "h(t) = 480<BR>\n" );
document.write( "-16t^2 + 80t + 384 = 480<BR>\n" );
document.write( "-16t^2 + 80t + 384 - 480 = 0<BR>\n" );
document.write( "-16t^2 + 80t - 96 = 0<BR>\n" );
document.write( "Simplify, divide by -16<BR>\n" );
document.write( "t^2 - 5t + 6 = 0<BR>\n" );
document.write( "Factors to <BR>\n" );
document.write( "(t-3)(t-2) = 0<BR>\n" );
document.write( "At 480 ft twice<BR>\n" );
document.write( "t = 2 sec on the way up<BR>\n" );
document.write( "and<BR>\n" );
document.write( "t = 3 sec on the way down </SPAN>\n" );
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