document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=130910>Question 130910</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the value for n for which the sum 1+3+9+...to n terms is 364 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #95525 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=95525\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find the value for n for which the sum 1+3+9+...to n terms is 364<BR>\n" );
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document.write( "It's a geometric series with r = 3 and a(1) = 1<BR>\n" );
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document.write( "S(n) = a(1)[r^(n+1) - 1]/[r - 1]<BR>\n" );
document.write( "364 = 1[3^(n+1) - 1] /2<BR>\n" );
document.write( "3^(n+1) -1 = 728<BR>\n" );
document.write( "3^(n+1) = 729<BR>\n" );
document.write( "(n+1)log3 = log729<BR>\n" );
document.write( "n+1 = log729/log3<BR>\n" );
document.write( "n+1 = 6<BR>\n" );
document.write( "n = 5<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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