(x^2y+xy)-3(x^2y-xy)-4x^2y 化简 其中x=1 y=-1

题目

(x^2y+xy)-3(x^2y-xy)-4x^2y 化简 其中x=1 y=-1

答案

2(x^2y+xy)-3(x^2y-xy)-4x^2y
=2x²y+2xy-3x²y+3xy-4x² y
=-5x²y+5xy
=5-5
=0