=[(a+1)/(a+1)(a^2-a+1)-(1-a)/(a^3-1)]/[(a^4-a^2-2)/[(a^2)^3-1-(a^4+a^2+1]
=[(a+1)/(a^3+1)+(a-1)/(a^3-1)]/{(a^4-a^2-2)/[(a^2-1)(a^4+a^2+1)-(a^4+a^2+1)]}
=[(a+1)(a^3-1)+(a-1)(a^3+1)]/(a^6-1)]X[(a^2-2)(a^4+a^2+1)/(a^4-a^2-2)]
=[(a+1)(a^3-1)+(a-1)(a^3+1)]/(a^2-1)(a^4+a^2+1)X[(a^2-2)(a^4+a^2+1)/(a=[(a+1)/(a+1)(a^2-a+1)-(1-a)/(a^3-1)]/[(a^4-a^2-2)/[(a^2)^3-1-(a^4+a^2+1]
=[(a+1)/(a^3+1)+(a-1)/(a^3-1)]/{(a^4-a^2-2)/[(a^2-1)(a^4+a^2+1)-(a^4+a^2+1)]}
=[(a+1)(a^3-1)+(a-1)(a^3+1)]/(a^6-1)]X[(a^2-2)(a^4+a^2+1)/(a^4-a^2-2)]
=[(a+1)(a^3-1)+(a-1)(a^3+1)]/(a^2-1)(a^4+a^2+1)X[(a^2-2)(a^4+a^2+1)/(a^4-a^2-2)]
=(a^4-a+a^3-1+a^4+a-a^3-1)/(a^2-1)X[(a^2-2)/(a^4-a^2-2)]
=[2(a^4-1)(a^2-2)]/[(a^2-1)(a^4-a^2-2)]
=2(a^2-1)(a^2+1)(a^2-2)/[(a^2-1)(a^4-a^2+2)]
=2(a^4-2a^2+a^2+2)/(a^4-a^2+2)
=2