document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1099275>Question 1099275</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A rock is thrown upward with a velocity of 25 meters per second from the top of a 20 meter high cliff, and it misses the cliff on the way back down. When will the rock be 7 meters from the water, below? Round your answer to two decimal places </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #713706 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=713706\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the equation is h(t)=-4.9t^2+25t+20<BR>\n" );
document.write( "That equals 7 when the rock is 7 meters above the water.<BR>\n" );
document.write( "Therefore -4.9t^2+25t+13=0=4.9 t^2-25t-13<BR>\n" );
document.write( "t=(1/9.8)(25+/- sqrt (625+254.8); sqrt term is 29.66<BR>\n" );
document.write( "t=54.66/9.8=5.58 sec.<BR>\n" );
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