document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1058404>Question 1058404</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If A and B are 3×6 matrices, and CC is a 9×3 matrix, which of the following are defined?\r<BR>\n" );
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document.write( "A. A+C<BR>\n" );
document.write( "B. CA<BR>\n" );
document.write( "C. BC<BR>\n" );
document.write( "D. B-A<BR>\n" );
document.write( "E. CB-A </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #673450 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=673450\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I think instead of CC, you just meant to write C.\r<BR>\n" );
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document.write( "A+C is NOT defined since A is a 3x6 matrix while C is a 9x3 matrix. The dimensions don't match up. Both rows and columns must be the same value (eg: both need to be 3x6 matrices) for it to work.\r<BR>\n" );
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document.write( "CA is defined because C is 9x3 while A is 3x6. The inner dimensions, both \"3\", match up. So multiplication is allowed here.\r<BR>\n" );
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document.write( "BC is NOT defined because B is 3x6 while C is 9x3. The inner dimensions of 6 and 9 do NOT match up. \r<BR>\n" );
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document.write( "B-A is defined because both A and B are the same size: 3x6\r<BR>\n" );
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document.write( "CB is defined for similar reasons that CA is defined. CB is going to be a 9x6 matrix while A is a 3x6 matrix. The dimensions don't match up. So CB-A is NOT defined.\r<BR>\n" );
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document.write( "To summarize, the following answers are<BR>\n" );
document.write( "CA<BR>\n" );
document.write( "B-A\r<BR>\n" );
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document.write( "Everything else is undefined.  </SPAN>\n" );
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