(1/2x)²*(-4y²)+(1/2xy)²= -2x²y²+(1/2xy)²=(-3/2)(xy)²-1/3xy[6xy-3(xy-1/2x²y) ] = -1/3xy(3xy+3/2x²y)= -x²y²-1/2x^3y²请问第一题的最后（xy)^2，能不能写成x²y²？