Your problem → (x^8+2x^4+1)+(2x^4+x^2+1)
(x^8+2x^4+1)+(2x^4+x^2+1)
=x^8 + 2x^4 + 1 + 2x^4 + x^2+1
=x^8+2x^4+2x^4+x^2+1+1
=x^8+4x^4+x^2+2
