[9^(4n+2)-9^(4n+1)]/81^(2n-1)

[9^(4n+2)-9^(4n+1)]/81^(2n-1)

=[9*9^(4n+1)-9^(4n+1)]/9^(4n-2)

=[8*9^(4n+1)]/9^(4n-2)

=[8*9^(+1)]/9^(-2)

=8*9^3

=5832

原式＝9^(4n+2)-9^(4n+1)/9^(4n-2)分子上提出来9^(4n+1)得到9^(4n+1)(9-1)与分母约分得9^3（9-1）=27*8=216

9^(4n-2)[9^4-9^3]/9^(4n-2)=9^4-9^3=8*9^3=5832

[9^(4n+2)-9^(4n+1)]/81^(2n-1)
=[9^(4n+2)-9^(4n+1)]/(9^2)^(2n-1)
=[9^(4n+2)-9^(4n+1)]/9^((2n-1)*2)
=9^4-9^3
=8*9^3
=5832