document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=681567>Question 681567</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find An for the arithmetic series with S16 =-288 and a1=-21 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #422698 by </B><A HREF=/tutors/aboutme.mpl?userid=Jolliano><B>Jolliano(16)</B></A><img src=\"/images/stars/stars-06.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Jolliano><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=Jolliano><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=422698\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> T16 = a +(16 - 1)d<BR>\n" );
document.write( "T16 = 21 + (15)d Sn = (n/2)(a + l)<BR>\n" );
document.write( "where l is the last term among the terms in the sum. <BR>\n" );
document.write( "In the case our last term would be T16. Therefore<BR>\n" );
document.write( "S16 = (16/2)(21 +[21 +15d]) = 288<BR>\n" );
document.write( "(8)(21 + 21 + 15d) = 288<BR>\n" );
document.write( "(21 + 21 + 15d) = 288/8<BR>\n" );
document.write( "42 + 15d = 36<BR>\n" );
document.write( "15d = 36 - 42 = -6<BR>\n" );
document.write( "d = -6/15 = -2/5 = -0.4 Therefore,<BR>\n" );
document.write( "An or Tn or Un = a + (n - 1)d <BR>\n" );
document.write( "An or Tn or Un = 21 + (n -1)(-0.4)<BR>\n" );
document.write( "= 21 - 0.4(n - 1) </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );