What is the factor of X power 4 +x square + 1

Answer 1

(x^2+1)^2 = x^4+2x^2+1
so,
x^4+x^2+1 = (x^2+1)^2 - x^2
= (x^2+1+x)(x^2+1-x)

No linear factors with rational coefficients.