If x + y = - Z, then the value of (x ^ 2-y ^ 2) + (XZ YZ) is___

If x + y = - Z, then the value of (x ^ 2-y ^ 2) + (XZ YZ) is___

x+y=-z
(x^2-y^2)+(xz-yz)
=(x+y)(x-y)+z(x-y)
=-z(x-y)+z(x-y)
=0