先化简,再求值:3xy-(x^2 y+1/2x^2 y)-(xy-x^2 y-3),其中x=1,y=-2_数学解答

先化简,再求值:3xy-(x^2 y+1/2x^2 y)-(xy-x^2 y-3),其中x=1,y=-2

人气：379 ℃　时间：2020-06-20 13:45:54

解答

3xy-(x^2 y+1/2x^2 y)-(xy-x^2 y-3)
=3xy-x^2 y-1/2x^2 y-xy+x^2 y+3
=2xy-1/2x^2 y+3
=2*1*(-2)-1/2*1*(-2)+3
=-4+1+3
=0