Question 113568
I guess you need to simplify this expression.

{{{27a^3b-12ab}}}.....factor out common {{{3ab}}}

{{{3ab(9a^2-4)}}}......{{{9=3^2}}} and {{{4=2^2}}}, so we can substitute it

{{{3ab((3a)^2- 2^2)}}}.....factorize {{{(3a)^2- 2^2}}}; it is equal to {{{(3a- 2)(3a+2)}}} 

{{{3ab(3a- 2)(3a + 2)}}}