this is the difference of two squares
\(= (x^2-6)(x^2+6)\\ =(x-\sqrt 6)(x+\sqrt 6)(x^2+6)\)
You can only go further than this if you accept complex (imaginary) roots.
This is the sum of 2 cubes \((4c)^3+1^3\)
I expect you can look at the link below and work this one out for yourself. :)