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