document.write( "Question 575851: Suppose A is a 5 x 3 matrix, B is an r x s matrix and C is a 4 x 5 matrix. If At BC is defined, which one is true? ( the t after A means inverse)
\n" ); document.write( "1) the size of At BC is 3 x 5
\n" ); document.write( "2) r = 2, s = 5
\n" ); document.write( "3) r = 3, s = 4
\n" ); document.write( "4) r = 3, s = 5
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Algebra.Com's Answer #369640 by jim_thompson5910(35256)\"\" \"About 
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In order for BC to be defined, B must have 4 columns. So s = 4. This means that the resulting matrix BC is a r x 5 matrix\r
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\n" ); document.write( "\n" ); document.write( "Matrix A is a 5 x 3 matrix. So \"A%5ET\" is a 3 x 5 matrix since the transpose flips the rows and columns.\r
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\n" ); document.write( "\n" ); document.write( "So BC must have 5 rows in order for \"A%5ET%2ABC\" to be defined. This therefore means that \"A%5ET%2ABC\" is a 3 x 5 matrix\r
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\n" ); document.write( "\n" ); document.write( "So the answer is choice 1)
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