3x^2y-[2x^2y-(2xyz-x^2y)-4x^2z-xyz],其中x=-2,y=-3,z=1先化简,再求值.

问题描述:

3x^2y-[2x^2y-(2xyz-x^2y)-4x^2z-xyz],其中x=-2,y=-3,z=1
先化简,再求值.

3x^2y-[2x^2y-(2xyz-x^2y)-4x^2z-xyz]=3x^2y-2x^2y+(2xyz-x^2y)+4x^2z+xyz=x^2y+2xyz-x^2y+4x^2z+xyz=3xyz+4x^2z=3*(-2)(-3)*1+4*(-2)^2*1=18+16=34供参考

3x^2y-[2x^2y-(2xyz-x^2y)-4x^2z-xyz]=3x^2y-(2x^2y-2xyz+x^2y-4x^2z-xyz)=3x^2y-2x^2y+2xyz-x^2y+4x^2z+xyz=3x^2y-2x^2y-x^2y+2xyz+xyz+4x^2z=3xyz+4x^2z=3×(-2)×(-3)×1+4×(-2)^2×1=18+16=34