document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=394787>Question 394787</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me solve this:\r<BR>\n" );
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document.write( "A ball is thrown vertically upward from the top of a building 32 feet tall with an initial velocity of 16 feet per second. The distance s (in feet) of the ball from the ground after t seconds is s=32+16t-16t^2.\r<BR>\n" );
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document.write( "a. after how many seconds does the ball strike the ground?\r<BR>\n" );
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document.write( "b. after how many seconds does 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 #280111 by </B><A HREF=/tutors/aboutme.mpl?userid=nerdybill><B>nerdybill(7384)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nerdybill><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=nerdybill><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=280111\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A ball is thrown vertically upward from the top of a building 32 feet tall with an initial velocity of 16 feet per second. The distance s (in feet) of the ball from the ground after t seconds is s=32+16t-16t^2. <BR>\n" );
document.write( "a. after how many seconds does the ball strike the ground? <BR>\n" );
document.write( "set s to zero and solve for t:<BR>\n" );
document.write( "s=32+16t-16t^2<BR>\n" );
document.write( "0=32+16t-16t^2<BR>\n" );
document.write( "0=2+t-t^2<BR>\n" );
document.write( "t^2-t-2=0<BR>\n" );
document.write( "(t-2)(+1) = 0<BR>\n" );
document.write( "t = {-1, 2}<BR>\n" );
document.write( "the -1 is an extraneous solution leaving us with:<BR>\n" );
document.write( "t = 2 seconds<BR>\n" );
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document.write( "b. after how many seconds does the ball pass the top of the building on its way down?<BR>\n" );
document.write( "set s = 32 and solve for t:<BR>\n" );
document.write( "s=32+16t-16t^2<BR>\n" );
document.write( "32=32+16t-16t^2<BR>\n" );
document.write( "0=16t-16t^2<BR>\n" );
document.write( "0=t-t^2<BR>\n" );
document.write( "0=t(1-t)<BR>\n" );
document.write( "t = {0,1}<BR>\n" );
document.write( "the 0 represents when it was first thrown<BR>\n" );
document.write( "so, 1 second is your answer<BR>\n" );
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