document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1041318>Question 1041318</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If S8 = 1530 and r = 2, what is a1?\r<BR>\n" );
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document.write( "3<BR>\n" );
document.write( "6<BR>\n" );
document.write( "9<BR>\n" );
document.write( "12 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #656282 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=656282\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A1 = 6<BR>\n" );
document.write( "here's why.<BR>\n" );
document.write( "formula for Sn = A1 * (1 - r^n) / (1 - r)<BR>\n" );
document.write( "r = 2<BR>\n" );
document.write( "n = 8<BR>\n" );
document.write( "S8 = 1530<BR>\n" );
document.write( "formula becomes 1530 = A1 * (1 - 2^8) / (1 - 2)<BR>\n" );
document.write( "simplify to get 1530 = A1 * (-255 / (-1))<BR>\n" );
document.write( "simplify further to get 1530 = A1 * 255<BR>\n" );
document.write( "divide both sides of the equation by 255 to and solve for A1 to get A1 = 1530 / 255 = 6<BR>\n" );
document.write( "A1 = 6<BR>\n" );
document.write( "S8 = 6 * (1 - 2^8) / (1 - 2) = 6 * -255 / -1 = 6 * 255 = 1530<BR>\n" );
document.write( "solution is confirmed as good.<BR>\n" );
document.write( "A1 = 6 </SPAN>\n" );
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