(c^2 − a^2 − b^2)^2 − 4a^2b^2.

Answer 1

I see difference of squares
(c^2 − a^2 − b^2)^2 − 4a^2b^2
= (c^2 − a^2 − b^2 + 2ab)*((c^2 − a^2 − b^2 - 2ab)
= (c^2 - (a^2 - 2ab + b^2))*(c^2 - (a^2 + 2ab + b^2) )
= (c^2 - (a-b)^2 )*(c^2 - (a+b)^2 )

at the moment I see nothing else

Answer 2

= (c-(a-b))(c+(a-b))*(c-(a+b))(c+(a+b))
= (c-a+b)(c+a-b)(c-a-b)(c+a+b)