<PRE><B>Question 766025</B>
6x-4y+5z=31
5x+2y+2z=13
x+y+z=2 
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x+y+z=2
solve for z
z=2-x-y
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substitute for z in second equation
5x+2y+2*(2-x-y)=13
5x+2y+4-2x-2y=13
3x=9
x=3
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substitute for z and x in equation 1
6*3 -4y +5*(2-3-y)=31
18 -4y +10 -15 -5y = 31
-9y +13 = 31
-9y = 18
y = -2
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substitute x=3 and y=-2 into third equation
3-2+z=2
1+z=2
z=1
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check values in first, second and third equations
6*3 -4*(-2) +5*1 = 31
18 +8 +5 = 31
31 = 31     equation 1 checks
++++++++++++++++++++++++++++++++++++++++
5*3 +2*(-2) + 2*1 = 13
15 -4 +2 = 13
13 = 13     equation 2 checks
+++++++++++++++++++++++++++++++++++++++++
3 -2 + 1 = 2
2 = 2       equation 3 checks
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x=3, y=-2, z=1

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