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问题描述:
化简求值:2(x的2次方乘y+xy)-3(x的2次方乘y-xy)-4x的2次方乘y,其中x=1,y=-1
2(x^2y+xy)-3(x^2y-xy)-4x^2y =2x^2y+2xy-3x^2y+3xy-4x^2y =-5x^2y+5xy x=1,y=-1 =-5*1*(-1)+5(-1)*1 =5-5=0