We are given a system of three linear equations with three variables, $x$, $y$, and $z$. The system is: $x + 2y + z = 4$ (1) $-x - y + 2z = 2$ (2) $2x + y + 3z = 6$ (3) We need to find the values of $x$, $y$, and $z$ that satisfy all three equations.

AlgebraLinear EquationsSystems of EquationsGaussian EliminationVariable Elimination
2025/4/20

1. Problem Description

We are given a system of three linear equations with three variables, xx, yy, and zz. The system is:
x+2y+z=4x + 2y + z = 4 (1)
xy+2z=2-x - y + 2z = 2 (2)
2x+y+3z=62x + y + 3z = 6 (3)
We need to find the values of xx, yy, and zz that satisfy all three equations.

2. Solution Steps

First, add equations (1) and (2) to eliminate xx:
(x+2y+z)+(xy+2z)=4+2(x + 2y + z) + (-x - y + 2z) = 4 + 2
y+3z=6y + 3z = 6 (4)
Next, multiply equation (1) by -2 and add it to equation (3) to eliminate xx:
2(x+2y+z)+(2x+y+3z)=2(4)+6-2(x + 2y + z) + (2x + y + 3z) = -2(4) + 6
2x4y2z+2x+y+3z=8+6-2x - 4y - 2z + 2x + y + 3z = -8 + 6
3y+z=2-3y + z = -2 (5)
Now, we have a system of two equations with two variables, yy and zz:
y+3z=6y + 3z = 6 (4)
3y+z=2-3y + z = -2 (5)
Multiply equation (4) by 3:
3(y+3z)=3(6)3(y + 3z) = 3(6)
3y+9z=183y + 9z = 18 (6)
Add equations (5) and (6) to eliminate yy:
(3y+z)+(3y+9z)=2+18(-3y + z) + (3y + 9z) = -2 + 18
10z=1610z = 16
z=1610=85z = \frac{16}{10} = \frac{8}{5}
Substitute the value of zz into equation (4) to find yy:
y+3(85)=6y + 3(\frac{8}{5}) = 6
y+245=6y + \frac{24}{5} = 6
y=6245=305245=65y = 6 - \frac{24}{5} = \frac{30}{5} - \frac{24}{5} = \frac{6}{5}
Substitute the values of yy and zz into equation (1) to find xx:
x+2(65)+85=4x + 2(\frac{6}{5}) + \frac{8}{5} = 4
x+125+85=4x + \frac{12}{5} + \frac{8}{5} = 4
x+205=4x + \frac{20}{5} = 4
x+4=4x + 4 = 4
x=0x = 0

3. Final Answer

x=0x = 0
y=65y = \frac{6}{5}
z=85z = \frac{8}{5}

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