document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=565548>Question 565548</A>: <I><SPAN STYLE=\"word-break: break-all;\"> find the sum of the first 30 terms of  4+7+10+13+16+19.... </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #365872 by </B><A HREF=/tutors/aboutme.mpl?userid=htmentor><B>htmentor(1343)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=htmentor><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=htmentor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=365872\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> find the sum of the first 30 terms of  4+7+10+13+16+19....<BR>\n" );
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document.write( "This is an arithmetic sequence with a_1 = 4, and a common difference of 3.<BR>\n" );
document.write( "The formula for the n-th term is:<BR>\n" );
document.write( "a_n = a_1 + (n-1)d<BR>\n" );
document.write( "a_n = 4 + 3(n-1) = 3n + 1<BR>\n" );
document.write( "So the 30th term is a_30 = 3*30 + 1 = 91<BR>\n" );
document.write( "The sum of the 1st n terms of an arithmetic sequence is:<BR>\n" );
document.write( "S_n = (n/2)(a_1 + a_n)<BR>\n" );
document.write( "So S_30 = (30/2)(4+91) = 95*15 = 1425 </SPAN>\n" );
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