已知（xy²+3y³-x²y）-(-2x²y+y³+xy²),其中x=2,y=-3

已知（xy²+3y³-x²y）-(-2x²y+y³+xy²),其中x=2,y=-3
已知（xy²+3y³-x²y）-(-2x²y+y³+xy²),其中x=2,y=-3

已知（xy²+3y³-x²y）-(-2x²y+y³+xy²),其中x=2,y=-3
原式子=xy²+3y³-x²y+2x²y-y³-xy²
=2y^3+x^2y
把x=2,y=3代入
=2*3^3+2^2 *3
=54+12=66

（xy²+3y³-x²y）-(-2x²y+y³+xy²)
=xy²+3y³-x²y+2x²y-y³-xy²
=2y³+x²y
=2*（-3）^3+2^2*(-3)
=-54-12
=-66