= x^10 - x + x^5 - x^2 + x^2 + x + 1
= x ( x^9 - 1 ) + x^2 (x^3 - 1 ) + x^2 + x + 1
= x [ ( x^3 - 1) ( x^6 + x^3 + 1 )] + x^2 ( x - 1 )(x^2 + x + 1 ) + x^2 + x + 1
= x ( x - 1 )(x^2 + x + 1 )(x^6 + x^3 + 1) + x^2 (x-1 )(x^2 + x+ 1 ) + x^2 + x + 1
= (x^2 + x + 1 )[ x(x-1)(x^6 + x^3 + 1 ) + x^2 + 1 )
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