document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=874159>Question 874159</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Is there an easy way to memorize the formulas for geometric and arithmetic series & sequences and to figure out a specific term? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #527351 by </B><A HREF=/tutors/aboutme.mpl?userid=richwmiller><B>richwmiller(17219)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=richwmiller><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=richwmiller><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=527351\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> It helps if you understand what they mean and have used them a few times.<BR>\n" );
document.write( "Arithmetic <BR>\n" );
document.write( "if you know the last term use  S = ½(a + an)n<BR>\n" );
document.write( "S = ½(2a + (n-1)d)n<BR>\n" );
document.write( "an = a + (n - 1)d<BR>\n" );
document.write( "  <BR>\n" );
document.write( "Geometric <BR>\n" );
document.write( "Tn = t * r^(n - 1)<BR>\n" );
document.write( "S=t*(1 - r^n)/(1 - r)<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );