document.write( "Question 162861: Solve by substitution or elimination:
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document.write( "3x-4y+2z=-2
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document.write( "5x-y+3z=1
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document.write( "x+y-z=-5 \n" );
document.write( "
Algebra.Com's Answer #120066 by elima(1433)![]() ![]() ![]() You can put this solution on YOUR website! 3x-4y+2z=-2 \n" ); document.write( "5x-y+3z=1 \n" ); document.write( "x+y-z=-5 \n" ); document.write( "============= \n" ); document.write( "I'll go ahead and use elimination; \n" ); document.write( "Add 2 equations together to eliminate the y; \n" ); document.write( "5x-y+3z=1 \n" ); document.write( "x+y-z=-5 \n" ); document.write( "---------- \n" ); document.write( "6x+2z=-4 \n" ); document.write( "============= \n" ); document.write( "now add together 2 other equations to eliminate the y; \n" ); document.write( "3x-4y+2z=-2 \n" ); document.write( "x+y-z=-5 - multiply this equation by 4 so the y will eliminate; \n" ); document.write( "----------- \n" ); document.write( "4(x+y-z=-5) \n" ); document.write( "4x+4y-4z=-20 \n" ); document.write( "============= \n" ); document.write( "Now add the 2 equations; \n" ); document.write( "3x-4y+2z=-2 \n" ); document.write( "4x+4y-4z=-20 \n" ); document.write( "------------- \n" ); document.write( "7x-2z=-22 \n" ); document.write( "================ \n" ); document.write( "Now add the new equations together to eliminate a variable; \n" ); document.write( "6x+2z=-4 \n" ); document.write( "7x-2z=-22 \n" ); document.write( "--------- \n" ); document.write( "13x=-26 \n" ); document.write( "x=-2 \n" ); document.write( "============== \n" ); document.write( "Now we have what x equals, so we plug that into the equations then add them together to eliminate another variable; \n" ); document.write( "5x-y+3z=1 \n" ); document.write( "x+y-z=-5 \n" ); document.write( "============== \n" ); document.write( "-10-y+3z=1 \n" ); document.write( "-2+y-z=-5 \n" ); document.write( "---------- \n" ); document.write( "-12+2z=-4 \n" ); document.write( "2z=8 \n" ); document.write( "z=4 \n" ); document.write( "=========== \n" ); document.write( "Now that we have both x and z we can plug those into any equation and find y; \n" ); document.write( "x+y-z=-5 \n" ); document.write( "-2+y-4=-5 \n" ); document.write( "-6+y=-5 \n" ); document.write( "y=1 \n" ); document.write( "============= \n" ); document.write( "Check; \n" ); document.write( "-2+1-4=-5 \n" ); document.write( "-1-4=-5 \n" ); document.write( "-5=-5 \n" ); document.write( "check; \n" ); document.write( "5x-y+3z=1 \n" ); document.write( "-10-1+12=1 \n" ); document.write( "-11+12=1 \n" ); document.write( "1=1 \n" ); document.write( ":) \n" ); document.write( " \n" ); document.write( " |