document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=762889>Question 762889</A>: <I><SPAN STYLE=\"word-break: break-all;\"> how many terms of the series 24,20,16...must be taken that the sum may be 72? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #464276 by </B><A HREF=/tutors/aboutme.mpl?userid=sachi><B>sachi(548)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=sachi><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=sachi><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=464276\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the series is 24,20,16...in AP<BR>\n" );
document.write( "so a=1st term=24 & common difference =20-24=-4<BR>\n" );
document.write( "sum=72 is of say n terms<BR>\n" );
document.write( "then 72=n/2[2*24+(n-1)*-4]=n/2[48-4n+4]=n/2[52-4n]<BR>\n" );
document.write( "or 144=52n-4n^2<BR>\n" );
document.write( "or 4n^2-52n+144=0<BR>\n" );
document.write( "or n^2-13n+36=0<BR>\n" );
document.write( "or n^2-9n-4n+36=0<BR>\n" );
document.write( "or n(n-9)-4(n-9)=0<BR>\n" );
document.write( "or (n-9)(n-4)=0<BR>\n" );
document.write( "or n=9 or 4<BR>\n" );
document.write( " </SPAN>\n" );
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