3X+7Y+Z=5,4X+8Y+2Z=3,则X+Y+Z的值为

问题描述:

3X+7Y+Z=5,4X+8Y+2Z=3,则X+Y+Z的值为

3X+7Y+Z = 5 ①
4X+8Y+2Z = 3 ②
由②-①,就可得 X+Y+Z = -2