3x²y+{-2x²y-[-2xy+（x²y-4x²）-xy]+xy²}
=3x²y+{-2x²y-[-2xy+x²y-4x²-xy]+xy²}
=3x²y+{-2x²y+2xy-x²y+4x²+xy+xy²}
=3x²y-2x²y+2xy-x²y+4x²+xy+xy²
=3xy+xy²+4x²，
∵（x-2）²+|xy-4|=0，
∴x-2=0，xy-4=0，
∴x=2，y=2，
把x=2，y=2代入原式得：
=3×2×2+2×2²+4×2²
=36．