Factorise:

(i) H.C.F. of $9 x^{3}, 6 x^{2}$ and $12 x$ is $3 x$.

$\therefore 9 x^{3}-6 x^{2}+12 x=3 x\left(3 x^{2}-2 x+4\right)$

(ii) H.C.F. of $8 x^{3}, 72 x y$ and $12 x$ is $4 x$.

$\therefore 8 x^{3}-72 x y+12 x=4 x\left(2 x^{2}-18 y+3\right)$

(iii) H.C.F. of $18 a^{3} b^{3}, 27 a^{2} b^{3}$ and $36 a^{3} b^{2}$ is $9 a^{2} b^{2}$.

$\therefore 18 a^{3} b^{3}-27 a^{2} b^{3}+36 a^{3} b^{2}=9 a^{2} b^{2}(2 a b-3 b+4 a)$