[tex] {a}^{8} + {a}^{4} + 1 = \\
{a}^{8} + 2 {a}^{4} + 1 - {a}^{4} =
( {a}^{4} + 1) ^{2} - {a}^{4} =
( {a}^{4} + 1 - {a}^{2} )( {a}^{4} + 1 + {a}^{2} )[/tex]
