document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=379646>Question 379646</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A rose garden has 21 bushes in one row, 17 bushes in the next row, then 13, and so on. If there are 66 bushes in the garden, in how many rows are they planted? \r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #269585 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=269585\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Aritmetic sequence:<BR>\n" );
document.write( "c=a[1]-d<BR>\n" );
document.write( "c=21-(-4)=25<BR>\n" );
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document.write( "a[n]=dn+c<BR>\n" );
document.write( "a[n]=-4n+25<BR>\n" );
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document.write( "(n/2)(a[1]+a[n])=S[n]<BR>\n" );
document.write( "(n/2)(21-4n+25)=66<BR>\n" );
document.write( "n(46-4n)=132<BR>\n" );
document.write( "46n-4n^2=132<BR>\n" );
document.write( "4n^2-46n+132=0<BR>\n" );
document.write( "2n^2-23n+66=0<BR>\n" );
document.write( "(n-6)(2n-11)=0<BR>\n" );
document.write( "n=6 rows<BR>\n" );
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document.write( "Ed </SPAN>\n" );
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