Answer
$(x^{2}+6)(6x^{2}-1)$
Work Step by Step
$6x^{4}+35x^{2}-6$
... Searching for two factors of $ac=-36$ whose sum is $b=35,$
we find$\qquad 36$ and $-1.$
Rewrite the middle term and factor in pairs:
$=6x^{4}+36x^{2}-x^{2}-6=$
$=6x^{2}(x^{2}+6)-(x^{2}+6)$
=$(x^{2}+6)(6x^{2}-1)$