先化简,再求值 (xy²+3y³-x²y)—(-2x²y+y³+xy²)-4y³,其中x=2,y=3

问题描述:

先化简,再求值 (xy²+3y³-x²y)—(-2x²y+y³+xy²)-4y³,其中x=2,y=3

(xy²+3y³-x²y)—(-2x²y+y³+xy²)-4y³=xy²+3y³-x²y+2x²y-y³-xy²-4y³=-2y³+x²y=-2×3³+2²×3=-54+12=-42