document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=884554>Question 884554</A>: <I><SPAN STYLE=\"word-break: break-all;\"> how many terms of the A.P. 1,4,7,10,.... are needed to get the sum 715 ? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #534410 by </B><A HREF=/tutors/aboutme.mpl?userid=skartikey><B>skartikey(21)</B></A><img src=\"/images/stars/stars-07.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=skartikey><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=skartikey><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=534410\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> s=n/2{2a+(n-1)d}<BR>\n" );
document.write( "715=n/2{2X1+(n-1)3}<BR>\n" );
document.write( "1430=n(2+3n-3)<BR>\n" );
document.write( "3n^2-n-1430=0<BR>\n" );
document.write( "3n^2-(66-65)n-1430=0<BR>\n" );
document.write( "3n(n-22)-65(n-22)=0<BR>\n" );
document.write( "(n-22)(3n-65)=0<BR>\n" );
document.write( "=>n-22=0<BR>\n" );
document.write( "n=22<BR>\n" );
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