document.write( "Question 1029003: Can you help me solve this system of equations for a,b,c and d:\r
\n" ); document.write( "\n" ); document.write( "2a-4b+6c-2d=-6
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\n" ); document.write( "a+8b+2c+d=6
\n" ); document.write( "3a+6b+c+4d=2 \n" ); document.write( "

Algebra.Com's Answer #644083 by Edwin McCravy(20056) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "I'll solve it part of the way step by step.  \r\n" );
document.write( "You'll have to finish it by yourself:\r\n" );
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document.write( "b has already eliminated from the second equation,\r\n" );
document.write( "so the best way to begin is to eliminate b from\r\n" );
document.write( "two other equations. Multiply the 1st equation by 2\r\n" );
document.write( "and it will have a term -8b which is opposite the\r\n" );
document.write( "+8b in the 3rd equation, and they will cancel when\r\n" );
document.write( "added.\r\n" );
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document.write( "4a-8b+12c-4d=-12\r\n" );
document.write( " a+8b+ 2c+ d=  6\r\n" );
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document.write( "5a   +14c-3d= -6\r\n" );
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document.write( "Also multiply the 1st equation by 3 and it will have \r\n" );
document.write( "a term -12b. Then multiply the 4th equation through\r\n" );
document.write( "by 2 and it will have a term 12b which is opposite the\r\n" );
document.write( "-12b, and they will cancel when added.\r\n" );
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document.write( " 6a-12b+18c-6d=-18,\r\n" );
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document.write( " 6a+12b+ 2c+8d=  4\r\n" );
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document.write( "12a    +20c+2d=-14  \r\n" );
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document.write( "Taking these two new equations with the original equations,\r\n" );
document.write( "we now have a system of three equations and three unknowns.\r\n" );
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document.write( "Now eliminate one of those unknowns and you'll have a\r\n" );
document.write( "system with only two equations in two unknowns, which\r\n" );
document.write( "you can solve.  You finish:\r\n" );
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document.write( "I'll tell you the values for b = 1/2 and d = 3.  You find\r\n" );
document.write( "a and c by yourself.\r\n" );
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document.write( "Edwin

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