x⁸ - 2x⁶ + 2x² - 1 =
=x⁸ - 1 - 2x²(x⁴-1) =
=(x⁴ - 1)(x⁴+1) - 2x²(x²-1)(x²+1) =
=(x² - 1)(x² + 1)(x⁴+1) - 2x²(x-1)(x+1)(x²+1) =
=(x - 1)(x+1)(x² + 1)(x⁴+1) - 2x²(x-1)(x+1)(x²+1) =
=(x - 1)(x+1)(x² + 1)[(x⁴+1) - 2x²] =
=(x - 1)(x+1)(x² + 1)(x⁴ - 2x²+1) =
=(x - 1)(x+1)(x² + 1)(x²-1)² =
=(x - 1)(x+1)(x² + 1)(x-1)²(x+1)² =
=(x - 1)³(x+1)³(x² + 1)