a) ((x - 5) - 6x)((x - 5) + 6x) = (-5x - 5)(7x - 5) = -5(x + 1)(7x - 5)
б) (x² - 4y²) - (x - 2y) = (x - 2y)(x + 2y) - (x - 2y) = (x - 2y)(x + 2y - 1)
в) (3x)³ + (y²)³ = (3x + y²)(9x² - 3xy² + y⁴)