А) x^2 + 6x + 8 = x^2 + 4x + 2x + 8 = (x^2 + 4x) + (2x + 8) = x (x + 4) + 2 (x + 4) =
= (x + 2) (x + 4)
б) x^2 - 8x + 15 = x^2 - 5x - 3x + 15 = (x^2 - 5x) - (3x - 15) = x (x- 5) - 3(x - 5) = = (x -3) (x - 5)
в) x^2 + 3x + 2 = x^2 + x + 2x + 2 = (x^2 + x) + (2x + 2) = x (x + 1) + 2 (x + 1) =
= (x + 2) ( x + 1)
r) x^2 - 5x + 6 = x^2 - 2x - 3x + 6 = (x^2 - 2x) - (3x - 6) = x (x-2) - 3 (x - 2) =
= (x -3) (x - 2)