Объяснение:

[tex]x(x - 2) - 8 = (x + 2)(x - 4) \\ {x}^{2} - 2x - 8 = {x}^{2} - 4x + 2x - 8 \\ {x}^{2} - {x}^{2} - 2x + 4x - 2x = - 8 + 8 \\ 0 = 0[/tex]