Question

化简 2x-y-z x 2 -xy-xz+yz + 2y-x-z y 2 -xy-yz+xz + 2z-x-y z 2

Answer 1

原式=

(x-y)+(x-z)

(x-y)(x-z) +

(y-x)+(y-z)

(y-x)(y-z) +

(z-x)+(z-y)

(z-x)(z-y)

=

1

x-z +

1

x-y +

1

y-z +

1

y-x +

1

z-y +

1

z-x

=

1

x-z -

1

x-z +

1

x-y -

1

x-y +

1

y-z -

1

y-z

=0+0+0

=0．