\(a^4+a^2+1\)
\(=a^4-a+a^2+a+1\)
\(=a\left(a^3-1\right)+\left(a^2+a+1\right)\)
\(=a\left(a-1\right)\left(a^2+a+1\right)+\left(a^2+a+1\right)\)
\(=\left(a^2+a+1\right)\left[a\left(a-1\right)+1\right]\)
\(=\left(a^2+a+1\right)\left(a^2-a+1\right)\)
a4 + a2 +1 = a4 +2a2 + 1 - a2
= (a4 +2a2 + 1) - a2
= (a2 + 1)2 - a2
= (a2 + 1 - a)(a2 + 1 +a)