2(a-b)^2n*3x(b-a)^(2n-2)*4y(a-b)^3
=2(a-b)^2n*3x(a-b)^(2n-2)*4y(a-b)^3
=2*3x*4y(a-b)^[2n+(2n-2)+3]
=24xy(a-b)^(2n+2n-2+3)
=24xy(a-b)^(4n-1)