document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1067137>Question 1067137</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In Arithmetic series, the 3rd term is twice the 8th term. Find the sum of the first 25 terms </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #682341 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=682341\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The nth term of an arithmetic sequence is a(n) = a(1) + d(n-1), where a(1) is the first term and d is the common difference<BR>\n" );
document.write( ":<BR>\n" );
document.write( "a(3) = a(1) + d(3-1)<BR>\n" );
document.write( "a(8) = a(1) + d(8-1)<BR>\n" );
document.write( ":<BR>\n" );
document.write( "We are given<BR>\n" );
document.write( ":<BR>\n" );
document.write( "a(1) + 2d = 2(a(1) + 7d)<BR>\n" );
document.write( ":<BR>\n" );
document.write( "a(1) + 2d = 2a(1) + 14d<BR>\n" );
document.write( ":<BR>\n" );
document.write( "a(1) + 12d = 0<BR>\n" );
document.write( ":<BR>\n" );
document.write( "a(1) = -12d<BR>\n" );
document.write( "a(25) = a(1) + d(25-1)<BR>\n" );
document.write( ":<BR>\n" );
document.write( "The sum of the first n terms of an arithmetic sequence is S(n) = (n/2)(a(1) + a(n))<BR>\n" );
document.write( ":<BR>\n" );
document.write( "***************************************<BR>\n" );
document.write( "S(25) = (25/2)(-12d + (-12d)+(24d)) = 0<BR>\n" );
document.write( "***************************************<BR>\n" );
document.write( ":<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );