document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=142142>Question 142142</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the sum of the first nine terms of the arithmetic series.<BR>\n" );
document.write( "2 - 5 - 12 - 19 - ... </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #103495 by </B><A HREF=/tutors/aboutme.mpl?userid=nabla><B>nabla(475)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nabla><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=103495\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The sum of the first n terms of an arithmetic progression is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=na%2B%28n%28n-1%29r%29%2F2 ALIGN=MIDDLE  ALT=\"na%2B%28n%28n-1%29r%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
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document.write( "n=9    <--- # of terms<BR>\n" );
document.write( "a=2  <--starting term<BR>\n" );
document.write( "r=-7  <--- common difference between terms\r<BR>\n" );
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document.write( "s=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=9%2A%282%29%2B9%289-1%29%28-7%29%2F2 ALIGN=MIDDLE  ALT=\"9%2A%282%29%2B9%289-1%29%28-7%29%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=18-252=-234 ALIGN=MIDDLE  ALT=\"18-252=-234\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "We can check by iterating every term:<BR>\n" );
document.write( "2-5-12-19-26-33-40-47-54=-234 </SPAN>\n" );
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