document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=371103>Question 371103</A>: <I><SPAN STYLE=\"word-break: break-all;\"> strings of length 9 with elements being a, b or c. How many strings will contain at least 6 b’s\r<BR>\n" );
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document.write( "I know the answer is 835 but I am looking for a formula or clarification on how the answer is derived please. Thank you. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #264426 by </B><A HREF=/tutors/aboutme.mpl?userid=edjones><B>edjones(8007)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=edjones><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=edjones><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=264426\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> expand(b+a+c)^9<BR>\n" );
document.write( "1 b^9<BR>\n" );
document.write( "2*9 b^8...<BR>\n" );
document.write( "2*36+72 b^7...<BR>\n" );
document.write( "2*84+252*2 b^6...<BR>\n" );
document.write( "-------add<BR>\n" );
document.write( "835 strings will contain at least 9 b's.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Ed </SPAN>\n" );
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