Step 1 :
To factor $ 27x^{3}-36x^{2}-12x+16 $ we can use factoring by grouping:
Group $ \color{blue}{ 27x^{3} }$ with $ \color{blue}{ -36x^{2} }$ and $ \color{red}{ -12x }$ with $ \color{red}{ 16 }$ then factor each group.
$$ \begin{aligned} 27x^{3}-36x^{2}-12x+16 = ( \color{blue}{ 27x^{3}-36x^{2} } ) + ( \color{red}{ -12x+16 }) &= \\ &= \color{blue}{ 9x^{2}( 3x-4 )} + \color{red}{ -4( 3x-4 ) } = \\ &= (9x^{2}-4)(3x-4) \end{aligned} $$Step 2 :
Rewrite $ 9x^{2}-4 $ as:
$$ 9x^{2}-4 = (3x)^2 - (2)^2 $$Now we can apply the difference of squares formula.
$$ I^2 - II^2 = (I - II)(I + II) $$After putting $ I = 3x $ and $ II = 2 $ , we have:
$$ 9x^{2}-4 = (3x)^2 - (2)^2 = ( 3x-2 ) ( 3x+2 ) $$