document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1144466>Question 1144466</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me solve this equation: nCr-3+3(nCr-2)+3(nCr-1)+nCr </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #765608 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=765608\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "Empirically (by looking at examples) the given expression is equivalent to (n+3)Cr.  e.g....<br><BR>\n" );
document.write( "6C3+3*6C4+3*6C5+6C6 = 20+3(15)+3(6)+1 = 84 = 9C6<BR>\n" );
document.write( "5C1+3*5C2+3*5C3+5C4 = 5+3(10)+3(10)+5 = 70 = 8C4<BR>\n" );
document.write( "7C2+3*7C3+3*7C4+7C5 = 21+3(35)+3(35)+21 = 252 = 10C5<br><BR>\n" );
document.write( "Proving it algebraically looks like a nightmare, unless there is some trick I don't see. </SPAN>\n" );
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