document.write( "Question 389508: I need to solve for a system of three variables, and this is the first time I've ever came across this so I don't really know if I'm doing this right...\r
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document.write( "So here is the system:
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document.write( "2x - y + 3z = 8
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document.write( "x - 6y - z = 0
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document.write( "-6x + 3y - 9z = 24 \r
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document.write( "I decided to get x taken care of first so I took the middle equation and it made x = 6y + z
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document.write( "And then I took x and plugged it in to the top equation so it would be 2(6y+z) - y + 3z = 8 and then it went to 12y + 2z - y + 3z = 8 and then 11y + 5z = 8 and then I got y = 5/11z +8/11
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document.write( "Then to get z I went ahead and plugged in x and y into the third equation, (which is where I think I made the wrong move...) then I got -36y - 6z + 15/11z + 24/11 - 9z = 24
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document.write( "Added like terms, and then that's where I got stumped. -6z + 15/11z is 9/11z, and then when you add the -9z it makes 0/11z? and if I actually did solve for z I really wouldn't get the first solution...
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document.write( "Can someone please help me point out where I went wrong and help me through this problem??? Thanks! \n" );
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Algebra.Com's Answer #276013 by mananth(16946)![]() ![]() You can put this solution on YOUR website! 2x - y + 3z = 8......................1 \n" ); document.write( "x - 6y - z = 0.......................2 \n" ); document.write( "-6x + 3y - 9z = 24 ..................3\r \n" ); document.write( "\n" ); document.write( ".. \n" ); document.write( "select (1) &(2) eliminate x \n" ); document.write( "select (2)&(3) eliminate x \n" ); document.write( ".. \n" ); document.write( "Then solve for y & z \n" ); document.write( "multiply (2) by -2 and add to (1)\r \n" ); document.write( "\n" ); document.write( "-2x+12y+2z=0 \n" ); document.write( "Add \n" ); document.write( "+11y+5z=8......................(3) \n" ); document.write( "... \n" ); document.write( "consider (2)&(3) eliminate x \n" ); document.write( "multiply (2)by 6 and add to (3) \n" ); document.write( "6x-36y-6z=0 \n" ); document.write( "add \n" ); document.write( "-33y-7z=24.....................(4) \n" ); document.write( ".. \n" ); document.write( "multiply (3) by 3 & add to 4 \n" ); document.write( "33y+15z=24 \n" ); document.write( "add \n" ); document.write( "+8z=48 \n" ); document.write( " \n" ); document.write( "plug z= 6 in (3) \n" ); document.write( "11y+5*6=8 \n" ); document.write( "11y+30=8 \n" ); document.write( "11y=-22 \n" ); document.write( " \n" ); document.write( "... \n" ); document.write( "plug y & z to get x \n" ); document.write( "2x - y + 3z = 8......................1 \n" ); document.write( "2x+2+18=8 \n" ); document.write( "2x+20=8 \n" ); document.write( "2x=-12 \n" ); document.write( " \n" ); document.write( "...\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "m.ananth@hotmail.ca \n" ); document.write( " |