<PRE><B>Question 1028392</B>
 4x+5y+z=23,
 2x-5y-z=-11,
 3x+y+3z=-5.
:
When you know that x = 2, you substitute 2 for x in the equations then
You can choose a pair of equations to find the other variables
using the 2nd and 3rd equations
2(2) - 5y - z -11
4 - 5y -z = -11
-5y - z = -11 - 4
-5y - z = -15
and
3(2) + y +3z = -5
y + 3z = -5 - 6
y + 3z = -11
multiply the 1st equation by 3, add to the above equation
-15y -3z = -45
 y + 3z = = -11
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-14y + 0 = -56
y = -56/-14
y = +4
Now substitute 4 for y and find x using either of the two variable equations
-5(4) - z = -15
-20 - z = -15
-z = -15 + 20
-z = 5
z = -5
:
:
Check all three solution in the original equations</PRE>