【(xy+2)(xy-2)-2(x^2y^2-2)】 ÷(xy)
=((xy)^2-4-2(xy)^2+4)/(xy)
=-(xy)^2/xy
=-xy
x=10,y=-25分之1
原式=-(10×-1/25)
=2/5
=0.4
【(xy+2)(xy-2)-2(x^2y^2-2)】 ÷(xy)
化简:原式=(x^2y^2-4-2x^2y^2+4)/xy
=-x^2y^2
=-4/25
=((xy)^2-4-2(xy)^2+4)/(xy)
=-(xy)^2/xy
=-xy