若3x+2y+4z=4,x-y+z=2,求x+4y+2y的值是多少

2(x-y+z)=2x-2y+2z=4
3x+2y+4z-2x+2y-2z
=x+4y+2z=4-4=0

3x+2y+4z=4,.............(1)
x-y+z=2,................(2)
(1)-(2)*2,得
x+4y+2z=0

3x+2y+4z=4......1
x-y+z=2.........2
将方程2x2：2x-2y+2z=4......3
方程1-方程2:x+4y+2y=0

题目应该错了，是“求x+4y+2z的值是多少”

3x+2y+4z=4 ①
x-y+z=2 ②

由②*2，2x-2y+2z=4③
由①-③，3x+2y+4z-2x+2y-2z=4-4
x+4y+2z=0