3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz,其中x=-2 y=-3 z=1

3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz,其中x=-2 y=-3 z=1
3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz,其中x=-2 y=-3 z=1

3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz,其中x=-2 y=-3 z=1
3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz
=3x²y-(2x²y-2xyz+x²z-4x²z)-xyz
=3x²y-2x²y+2xyz-x²z+4x²z-xyz
=x²y+3x²z+xyz
当x=-2 y=-3 z=1时,
原式=(-2)²×(-3)+3×(-2)²×1+(-2)×(-3)×1
=4×(-3)+3×4×1+(-2)×(-3)×1
=-12+12+6
=6

18

3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz
=3x²y-(2x²y-2xyz+x²z-4x²z)-xyz
=3x²y-2x²y+2xyz-x²z+4x²z-xyz
=x²y+xyz+3x²z
=x(xy+yz+3xz)
=-2(6-3-6)
=6

当x=-2 y=-3 z=1时
3x²y-[2x²y-(2xyz-x²z)-4x²z]-xyz=3x²y-2x²y+2xyz-x²z+4x²z-xyz=x²y+3x²z+xyz
=(-2)²×(-3)+3×(-2)²×1+(-2)×(-3)×1=-12+12+6=6

6

去括号，合并同类项，提取公因式，化简为x2（y+3z）+xyz，带入数值，y+3z=0，结果为6