先化简再求值:xyz-[-x^2y+(xyz-x^2z)]-x^2z,其中x=-1,y=-2,z=1

问题描述:

先化简再求值:xyz-[-x^2y+(xyz-x^2z)]-x^2z,其中x=-1,y=-2,z=1

原式=xyz+x^2y-xyz+x^2z-x^2z
=x^2y
=(-1)^2*(-2)
=-2

xyz-[-x^2y+(xyz-x^2z)]-x^2z
=xyz+x²y-xyz+x²z-x²z
=x²y
当x=-1,y=-2,z=1时
原式=-2