xy[4xy-2(xy+1/2x的2次方y)]
问题描述:
xy[4xy-2(xy+1/2x的2次方y)]
答
xy[4xy-2(xy+1/2x的2次方y)]
=xy[4xy-2xy-x的2次方y]
=xy[2xy-x²y]
=2x²y²-x³y²