(a+1)*(a-1)*(a^2+1)-(a^2-1)^2-2a^2

Question

(a+1)*(a-1)*(a^2+1)-(a^2-1)^2-2a^2

Answer 1

(а^2-1)*(а^2+1)-(а^4-2а^2+1)-2а^2=
а^4 - 1 - а^4 + 2а^2 - 1 - 2а^2 = -2