3x²y-[2xyz-(2xyz-x²yz)+3x²y],其中x=-4,y=1/2,z=3

题目

3x²y-[2xyz-(2xyz-x²yz)+3x²y],其中x=-4,y=1/2,z=3

答案

3x²y-[2xyz-(2xyz-x²yz)+3x²y]
=3x²y-[2xyz-2xyz+x²yz+3x²y]
=3x²y-x²yz-3x²y
=-x²yz
代入：
原式=-（-4)²×1/2×3
=-16×1/2×3
=-8×3
=-24