X² - 10x - 11 = (x - 5)² - 36 = (x - 5)² - 6² = (x - 5 - 6)(x - 5 + 6) =
= (x - 11)(x + 1)
x⁴ + 4y⁴ = (x² + 2y²)² - 4x²y² =(x² + 2y²)² - (2xy)² =(x² + 2y² - 2xy)(x² + 2y² +2xy)=
= (x² - 2xy + 2y²)(x² + 2xy + 2y²)
x² - 4x - 12 = (x - 2)² - 16 = (x - 2)² - 4² = (x - 2 - 4)(x - 2 + 4) = (x - 6)(x + 2)