问题 解答题

化简:(x-y-z)-(x+y-z)-(x+y-z).

答案

(x-y-z)-(x+y-z)-(x+y-z)

=x-y-z-x-y+z-x-y+z

=(1-1-1)x+(-1-1-1)y+(-1+1+1)z

=-x-3y+z.

选择题
单项选择题