Answer :

[tex]x^{6} + 2 x^{4} - 16 x^{2} - 32 =x^4(x^2+2)-16(x^2+2)=(x^2+2)(x^4-16)=\\ \\=(x^2+2)(x^4-4^2)=(x^2+2)(x^2-4)(x^2+4) =\\ \\=(x^2+2)(x^2+4)(x+2)(x-2) \\ \\ \\a^2-b^2 =(a-b)(a+b)[/tex]