document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1034471>Question 1034471</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If a stack of n layers of power poles contains four poles in the top layer and each layer contains one more pole than the layer above, find how many layers there are if the stack contains 184 poles. Please help, Im not sure which formula(s) to use. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #649122 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=649122\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> (1/2)n*(n+1) is the sum of all the numbers from 1 to n.<BR>\n" );
document.write( "From 1 to 3 is a total of 6, so the answer would be the stack of 190 poles. We just ignore the first 3.<BR>\n" );
document.write( "380=n(n+1)<BR>\n" );
document.write( "n^2+n-380=0<BR>\n" );
document.write( "(n+20)(n-19)=0<BR>\n" );
document.write( "positive root only, n=19<BR>\n" );
document.write( "16 layers, because we ignore the first 3.<BR>\n" );
document.write( "4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19=184 </SPAN>\n" );
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