(x^2-1)^2+6(x^2-1)+9=(x^2-1)*(x^2-1)*(x^2-1)+6x^2-6+9=x^4-2x^2+1+6x^2-6+9=
=x^4+4x^2+4=(x^2+2)*(x^2+2)
(x^2-1)^2+6(x^2-1)+9=(x^2-1)*(x^2-1)*(x^2-1)+6x^2-6+9=x^4-2x^2+1+6x^2-6+9=
=x^4+4x^2+4=(x^2+2)*(x^2+2)