4x2y-[6xy-2﹙4xy-2﹚-x2y]
=4x2y+x2y-6xy+8xy-4
=5x2y+2xy-4
I2x-1I+﹙y+2﹚2=0
x=1/2 y=-2
原式=5x2y+2xy-4=-5/2-2-4=-17/2