You can write it as (y²)² +12(y²)+36. It's easy to notice it's y[tex](y^2+6)[/tex] squared. Since you want to consider complex factors as well, you can see +6 as [tex] (i \sqrt{6})^2 [/tex]. Your Expression becomes [tex][(y+i \sqrt6)(y-i\sqrt6)]^2[/tex]
