Question

已知方程组2x-y+4z=2,x+y-z=4,则x-y+3z的值等于

Answer 1

2x-y+4z=2,(1)

x+y-z=4 (2)

两式相加得：

3x+3z=6

x+z=2 (3)

(2)×(2)-(1)得：

3y-6z=6

y-2z=2 (4)

(3)-(4)得：

x-y+3z=2-2=0