$$=(9x-3)^{8}-6x+9$$
$6561\left(3x-1\right)^{8}-6x+9$
$43046721x^{8}-114791256x^{7}+133923132x^{6}-89282088x^{5}+37200870x^{4}-9920232x^{3}+1653372x^{2}-157470x+6570$
