document.write( "Question 359550: The cost of six shirts and 2 pairs of trousers is 1320. While that of 3 shirts and 4 pairs of trousers is 1290. Find using a matrix method the cost of 2 shirts and 2 pairs of trousers. \n" ); document.write( "

Algebra.Com's Answer #256624 by Fombitz(32388) $\"\"$ $\"About$

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Let $\"S\"$ be the cost of the shirt, $\"T\"$ the trousers.
\n" ); document.write( " $\"6S%2B2T=1320\"$
\n" ); document.write( " $\"3S%2B4T=1290\"$
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\n" ); document.write( "[A]= $\"%28matrix%282%2C2%2C6%2C2%2C3%2C4%29%29\"$
\n" ); document.write( "[x]= $\"%28matrix%282%2C1%2CS%2CT%29%29\"$
\n" ); document.write( "[b]= $\"%28matrix%282%2C1%2C1320%2C1290%29%29\"$
\n" ); document.write( "[A][x]=[b]
\n" ); document.write( "[x]=[A]inv[b]
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\n" ); document.write( "det[A]= $\"18\"$
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\n" ); document.write( "[A]inv= $\"%281%2F18%29%2A%28matrix%282%2C2%2C4%2C-2%2C-3%2C6%29%29\"$
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\n" ); document.write( "[x]= $\"%28matrix%282%2C1%2CS%2CT%29%29=%28matrix%282%2C1%2C150%2C210%29%29\"$
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\n" ); document.write( "So then 2 shirts and 2 trousers would be
\n" ); document.write( " $\"P=2S%2B2T=2%28150%29%2B2%28210%29=300%2B420=highlight%28720%29\"$ \n" ); document.write( "

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