\[(x + 1)\left( x^{2} - x + 1 \right)\left( x^{6} - x^{3} + 1 \right) =\]
\[= \left( x^{3} - x^{2} + x + x^{2} - x + 1 \right)\left( x^{6} - x^{3} + 1 \right) =\]
\[= \left( x^{3} + 1 \right)\left( x^{6} - x^{3} + 1 \right) =\]
\[= x^{6 + 3} - x^{3 + 3} + x^{3} + x^{6} - x^{3} + 1 =\]
\[= x^{9} - x^{6} + x^{6} + 1 = x^{9} + 1.\]