document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1186930>Question 1186930</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the sum of the first eight terms of each of these geometric series.<BR>\n" );
document.write( "a) 729 + 243 + 81 + 27 + …<BR>\n" );
document.write( "b) 2 - 6 + 18 - 54 + … </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #817903 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=817903\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> s= a (1-r^(n+1))/(1-r)<BR>\n" );
document.write( "the first term has a=729 and r=(1/3), and n+1=8, since first term is ar^0<BR>\n" );
document.write( "so s=(729) (1-(1/3)^8)/(1-(1/3))<BR>\n" );
document.write( "=729 (1.49977) don't round<BR>\n" );
document.write( "=1093 (1/3)<BR>\n" );
document.write( "729+243+81+27+9+3+1+(1/3)=1093 (1/3)<BR>\n" );
document.write( "--<BR>\n" );
document.write( "this is r=(-3)<BR>\n" );
document.write( "s=2(1-(-3)^8/(1-(-3))<BR>\n" );
document.write( "=2*(1-6561)/4<BR>\n" );
document.write( "=-3280<BR>\n" );
document.write( "2-6+18-54+162-486+1458-4374=-3280\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );