document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=843423>Question 843423</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The sum of the first five terms of an arithmetic series is 25.  The sum of the first seven terms is 49.  What are the values of t1, t12 and S12? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #516254 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=516254\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> S = ½(2t1 + (n-1)d)n\r<BR>\n" );
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document.write( "25 = ½(2t1 + 4d)5,<BR>\n" );
document.write( "49 = ½(2t1+ 6d)7<BR>\n" );
document.write( "t1 = 1,   d = 2\r<BR>\n" );
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document.write( "S12 = ½(2 + (11)2)12=144<BR>\n" );
document.write( "tn = t1 + (n - 1)d<BR>\n" );
document.write( "t12= 1 + (11)2=23\r<BR>\n" );
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document.write( " </SPAN>\n" );
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