х^2 - 6х + 8 = x^2 - 2 * x * 3 + 3^2 - 3^2 + 8 = (x^2 - 6x + 9) - 9 + 8 = (x - 3)^2 - 1^2 = (x - 3 - 1)(x - 3 + 1) = (x - 4)(x - 2).
х^2 - 6х + 8 = x^2 - 2 * x * 3 + 3^2 - 3^2 + 8 = (x^2 - 6x + 9) - 9 + 8 = (x - 3)^2 - 1^2 = (x - 3 - 1)(x - 3 + 1) = (x - 4)(x - 2).