由（4x-2y-1）²+√(xy-2）=0可知 4x-2y-1=0 xy-2=0即 2x-y=1/2 xy=2所以 4x³y-4x²y²+xy³＝xy(4x²-4xy+y²)＝xy(2x-y)²＝2×(1/2)²＝1/2