document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1073519>Question 1073519</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Another operation that can be defined on sets A and B is the difference of the sets, denoted by \r<BR>\n" );
document.write( "\n" );
document.write( "A &#8722; B.<BR>\n" );
document.write( " Here is the formal definition of the difference of sets A and B. \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "A &#8722; B = {x | x is in A  and  x not in B} <BR>\n" );
document.write( " Thus \r<BR>\n" );
document.write( "\n" );
document.write( "A &#8722; B<BR>\n" );
document.write( " is the set of elements that belong to A but not to B. For instance, let \r<BR>\n" );
document.write( "\n" );
document.write( "A = {1, 2, 3, 7, 8}<BR>\n" );
document.write( " and \r<BR>\n" );
document.write( "\n" );
document.write( "B = {2, 7, 11}.<BR>\n" );
document.write( " Then \r<BR>\n" );
document.write( "\n" );
document.write( "A &#8722; B = {1, 3, 8}.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " Determine the difference, given that \r<BR>\n" );
document.write( "\n" );
document.write( "U = {1, 2, 3, 4, 5, 6, 7, 8, 9},<BR>\n" );
document.write( " \r<BR>\n" );
document.write( "\n" );
document.write( "A = {2, 4, 6, 8},<BR>\n" );
document.write( " and \r<BR>\n" );
document.write( "\n" );
document.write( "B = {1, 6, 8, 9}.<BR>\n" );
document.write( " (Enter your answers as a comma-separated list.)  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #688334 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=688334\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> We're given A = {2, 4, 6, 8} and B = {1, 6, 8, 9}. We want to find A - B.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Start with set A = {2, 4, 6, 8}. Look through this set and compare it to the numbers in set B. Notice how 6 and 8 are found in set B. Erasing those values gets us \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "A - B = {2, 4}\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Notes:<BR>\n" );
document.write( "1) The values 1 and 9 are ignored since they aren't in set A. <BR>\n" );
document.write( "2) The universal set U isn't really used much here.  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );