document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=847520>Question 847520</A>: <I><SPAN STYLE=\"word-break: break-all;\"> how many terms of the sequence  13,11,9..... makes the sum 45? Explain the answer </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #510514 by </B><A HREF=/tutors/aboutme.mpl?userid=swincher4391><B>swincher4391(1107)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=swincher4391><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=swincher4391><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=510514\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> sum from i =1 to n  of (15-2i) = 45\r<BR>\n" );
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document.write( "sum from i = 1 to n of 15  - 2* sum from i = 1 to n of i\r<BR>\n" );
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document.write( "15n - n(n+1) = 45\r<BR>\n" );
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document.write( "15n - n^2 + n = 45\r<BR>\n" );
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document.write( "n^2 -14n +45 = 0\r<BR>\n" );
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document.write( "(n-5)(n-9)\r<BR>\n" );
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document.write( "n=5,  n=9\r<BR>\n" );
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document.write( "Check:  13+11+9+7+5 = 45 \r<BR>\n" );
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document.write( "Check:  13+11+9+7+5+3+1+-1+-3 = 45\r<BR>\n" );
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document.write( "So 5 terms or 9 terms. <BR>\n" );
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