document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1188509>Question 1188509</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown vertically upward from the top of a building 64 feet tall with an initial velocity of 48 feet per second. The distances (in feet) of the ball from the ground<BR>\n" );
document.write( "after t seconds is s(t) = 64 + 48t - 1612.<BR>\n" );
document.write( "(a) After how many seconds does the ball strike the ground?<BR>\n" );
document.write( "(b) After how many seconds will the ball pass the top of the building on its way down? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #819622 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=819622\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The formula is s(t)=-16t^2+48t+64<BR>\n" );
document.write( "the ground is 0.<BR>\n" );
document.write( "so -16t^2+48t+64=0=t^2-3t-4, moving everything over and dividing by 16<BR>\n" );
document.write( "(t-4)(t+1)=0<BR>\n" );
document.write( "t=4 seconds.<BR>\n" );
document.write( "-<BR>\n" );
document.write( "want to know when s=64<BR>\n" );
document.write( "so -16t^2+48t+64=64<BR>\n" );
document.write( "or 16t^2=48t<BR>\n" );
document.write( "t=3 seconds <BR>\n" );
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document.write( "</TD></TR></TABLE>\n" );