document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=160073>Question 160073</A>: <I><SPAN STYLE=\"word-break: break-all;\"> is (0,1,-1) closed under addition?\r<BR>\n" );
document.write( "\n" );
document.write( "...and if you can explain how to do this, that would be great </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #118048 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=118048\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 0+1=1\r<BR>\n" );
document.write( "\n" );
document.write( "1+(-1)=0\r<BR>\n" );
document.write( "\n" );
document.write( "-1+0=-1\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Notice how the sum of every pair of numbers is a number in the set {0,1,-1}. So this means that the set is closed under addition. \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Remember, a set that is \"closed\" under addition means that you can add up ANY two numbers in that set and you will ALWAYS get a number in that set.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );