Question 313259
2x+ y-3z=-12
3x-2y-z=  3
-x+5y+2z=-3
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2x+ y-3z=-12 ( multiply by 2 to eliminate y)
3x-2y-z=  3. 
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4x+2y-6z+3x-2y-z= -24+3
7x-7z=-21.
x-z=-3
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3x-2y-z=  3 ( multiply by 5 to eliminate y)
-x+5y+2z=-3 ( multiply by 2) and add
15x-10y-5z-2x+10y+4z=15-6
13x-z=9.
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x-z=-3
13x-z=9
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13x-13z-13x+z=-39-9
-12z=-48
z= 4.
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plug the value of z in x-z = -3
x-4=-3
x=4-3
x=1.
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plug the values of x & z in the equation 2x+ y-3z=-12
2+y-12=-12
y=-2