document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1034544>Question 1034544</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me with this problem:A person standing close to the edge on the top of an 80-foot tower throws a ball with an initial speed of 64 feet per second. After t seconds, the height of the ball above the ground is <BR>\n" );
document.write( "s(t) = -16t2 +64t + 80<BR>\n" );
document.write( "a. After how many seconds will the ball reach its maximum height?<BR>\n" );
document.write( "b. How long will it take before the ball reaches the ground?<BR>\n" );
document.write( "c. What is the maximum height of the ball?<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #649281 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=649281\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A person standing close to the edge on the top of an 80-foot tower throws a ball with an initial speed of 64 feet per second. After t seconds, the height of the ball above the ground is<BR>\n" );
document.write( "s(t) = -16t^2 + 64t + 80<BR>\n" );
document.write( "a. After how many seconds will the ball reach its maximum height?<BR>\n" );
document.write( "Max height will occur on the axis of symmetry, <BR>\n" );
document.write( "find that using t = -b/(2a) where a=-16 and b=64<BR>\n" );
document.write( "t = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-64%29%2F%282%2A-16%29 ALIGN=MIDDLE  ALT=\"%28-64%29%2F%282%2A-16%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "t = 2 seconds<BR>\n" );
document.write( ":<BR>\n" );
document.write( "b. How long will it take before the ball reaches the ground?<BR>\n" );
document.write( "When the ball hits the ground, s(t) = 0, therefore<BR>\n" );
document.write( "-16t^2 + 64t + 80 = 0<BR>\n" );
document.write( "Simplify, divide by -16, then we can factor<BR>\n" );
document.write( "t^2 - 4t - 5 = 0<BR>\n" );
document.write( "(t-5)(t+1) = 0<BR>\n" );
document.write( "the positive solution is what we want here<BR>\n" );
document.write( "t = 5 sec to hit the ground<BR>\n" );
document.write( ":<BR>\n" );
document.write( "c. What is the maximum height of the ball?<BR>\n" );
document.write( "max height occurs after 2 sec, replace t with 2 in the original equation<BR>\n" );
document.write( "s(t) = -16(2^2) + 64(2) + 80<BR>\n" );
document.write( "s(t) = -64 + 128 + 80<BR>\n" );
document.write( "s(t) = 144 ft is the max height </SPAN>\n" );
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