(3y-2x)的3次方×(2x-3y)的2n+1次方÷(3y-2x)的2n+2次方
=-(2x-3y)^3×(2x-3y)^(2n+1)÷(2x-3y)^(2n+2)
=-(2x-3y)^(2n+1+3-2n-2)
=-(2x-3y)^2