x⁶ - x⁴ + 2x³ + 2x²
= x²(x⁴ - x² + 2x + 2)
= x²[(x⁴ - x²) + (2x + 2)]
= x²[x²(x² - 1) +2(x + 1)]
= x²[x²(x - 1)(x + 1) + 2(x + 1)]
= x²(x + 1)[x²(x - 1) + 2]
= x²(x + 1)(x³ - x² + 2)
= x²(x + 1)(x³ + x² - 2x² - 2x + 2x + 2)
= x²(x + 1)[(x³ + x²) - (2x² + 2x) + (2x + 2)]
= x²(x + 1)[x²(x + 1) - 2x(x + 1) + 2(x + 1)]
= x²(x + 1)²(x² - 2x + 2)