document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=864059>Question 864059</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the first term of arithmetic progression is 3. Given that the sum of the first 6 terms is 48 and that the sum of all the terms is 168,calculate the common difference,the number of terms in the sequence, and the last term </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #520780 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=520780\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> S = ½(2a + (n-1)d)n<BR>\n" );
document.write( "48 = ½(6 + (5)d)6,<BR>\n" );
document.write( "168 = ½(6 + (n-1)d)n<BR>\n" );
document.write( "d = 2,   n = 12\r<BR>\n" );
document.write( "\n" );
document.write( "an = a + (n - 1)d<BR>\n" );
document.write( "a12 =3 + (11)2<BR>\n" );
document.write( "a12=25<BR>\n" );
document.write( "check<BR>\n" );
document.write( "S = ½(a + an)n<BR>\n" );
document.write( "S = ½(3 + 25)12=168<BR>\n" );
document.write( "ok\r<BR>\n" );
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document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );