計算3xy[2xy-x(y-2)+x-1]

計算3xy[2xy-x(y-2)+x-1]

3xy[2xy-x(y-2)+x-1]
=3xy(2xy-xy+2x+x-1)
=3xy(xy+3x-1)
=3x^2y^2+9x^2y-3xy