若x+y=-z,则(x^2-y^2)+(xz-yz)的值为?
问题描述:
若x+y=-z,则(x^2-y^2)+(xz-yz)的值为?
答
(x^2-y^2)+(xz-yz)
=(x-y)(X+Y+Z)
x+y=-z,X+Y+Z=0
则(x^2-y^2)+(xz-yz)=0