Question

x+y-z=1 -x+y+z=2 x-y+z=3解三元一次方程组，要规范步骤

Answer 1

解由
x+y-z=1 ............................(1)
-x+y+z=2..........................(2)
x-y+z=3.............................(3)
由(1)+(2)
得2y=3
即y=3/2
由(1)+(3)
得2x=4
即x=2
由(2)+(3)
得2z=5
解得z=5/2
故方程组的解为x=2，y=3/2，z=5/2.

Answer 2

x+y-z=1和 -x+y+z=2两式相加得
2y=3
解y=3/2
-x+y+z=2和x-y+z=3两式相加得
2z=5
解z=5/2
x+y-z=1和x-y+z=3两式相加得
2x=4
解x=2

Answer 3