document.write( "Question 208211: SOLVE USING DETERMINANTS and CRAMER'S RULE\r
\n" ); document.write( "\n" ); document.write( "Three kilos of homegrown tobacco and 8 kilos of imported tobacco cost $39.70 ,and 5 kilos of homegrown tobacco and 6 kilos of imported tobacco cost $47.10. What is the cost per kilo for both kinds of tobacco?
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Algebra.Com's Answer #157514 by pjalgeb(9)\"\" \"About 
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REQUIRED: Find y(price of homegrown tobacco) and x(price of imported tobacco)\r
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\n" ); document.write( "\n" ); document.write( "SOLUTION:\r
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\n" ); document.write( "\n" ); document.write( " Amount HGT Amount of IMPT IMPT Price HGT Price Total Price
\n" ); document.write( " (kilos) (kilos) ($ per kilo) ($ per kilo) ($)\r
\n" ); document.write( "\n" ); document.write( " ______________________________________________________________________________\r
\n" ); document.write( "\n" ); document.write( "First Order | 3 : 8 : x : y : 3x+8y = 39.7 |\r
\n" ); document.write( "\n" ); document.write( "Second Order | 5 : 6 : x : y : 5x+6y = 47.1 |
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\n" ); document.write( "\n" ); document.write( "The following Equations can be derived from the total price column:\r
\n" ); document.write( "\n" ); document.write( " \"3x%2B8y+=+39.7+\" --> Equation 1 and \r
\n" ); document.write( "\n" ); document.write( " \"5x%2B6y+=+47.1+\" --> Equation 2
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\n" ); document.write( "Now we have two equations with two unknowns:\r
\n" ); document.write( "\n" ); document.write( " 3x+8y = 39.7 --> Equation 1
\n" ); document.write( " 5x+6y = 47.1 --> Equation 2\r
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\n" ); document.write( "\n" ); document.write( "The augmented 2x2 matrix for the above system of equations is:\r
\n" ); document.write( "\n" ); document.write( " | 3 8 | 39.7 |
\n" ); document.write( " | 5 6 | 47.1 |\r
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\n" ); document.write( "\n" ); document.write( "Using Cramer's Rule:\r
\n" ); document.write( "\n" ); document.write( "\"x+=+Dx%2FD\"
\n" ); document.write( "\"y+=+Dy%2FD\"\r
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\n" ); document.write( "\n" ); document.write( "First we solve for D, Dx and Dy:\r
\n" ); document.write( "\n" ); document.write( "D = | 3 8 | = 3(6) - 8(5) = 18 - 40 = - 22
\n" ); document.write( " | 5 6 |\r
\n" ); document.write( "\n" ); document.write( "since D is not 0 then we can proceed:\r
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\n" ); document.write( "\n" ); document.write( "Dx = | 39.7 8 | = 39.7(6) -8(47.1) = 238.2 - 376.8 = -138.6
\n" ); document.write( " | 47.1 6 | \r
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\n" ); document.write( "\n" ); document.write( "Dy = | 3 39.7 | = 3(47.1) - 5(39.7) = 141.3 - 198.5 = -57.2
\n" ); document.write( " | 5 47.1 | \r
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\n" ); document.write( "\n" ); document.write( "Now we can solve for x and y:\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+Dx%2FD+=+-138.6%2F-22++=+6.3+\"\r
\n" ); document.write( "\n" ); document.write( "\"y+=+Dy%2FD+=+-57.2%2F-22+++=+2.6+\"\r
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\n" ); document.write( "\n" ); document.write( "ANSWER:\r
\n" ); document.write( "\n" ); document.write( "Homegrown tobacco costs $2.60 per kilo while the imported ones costs $6.30 per kilo.\r
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