Разложите на множители 1)a^3-27+3a^2-9a2)b^3+125+2b+103)3x+6y-x^3-8y^3

1)   a - 27 + 3a - 9a = (a - 3) + 3a(a - 3) = 
      =  (a - 3)(a + 3a + 3) + 3a(a - 3) = (a - 3)(a + 3a + 9 + 3a) =
      = (a - 3)(a + 6a + 9) = (a - 3)(a + 3)

2)  b + 125 + 2b + 10 = b + 5 + 2(b + 5) =
      = (b + 5)(b - 5b + 5) + 2(b + 5) = (b + 5)(b - 5b + 25 + 2) =
      = (b + 5)(b - 5b + 27)

3)  3x + 6y - x - 8y = 3(x + 2y) - (x + (2y)) = 
     = 3(x + 2y) - (x + 2y)(x - 2xy + (2y)) = (x + 2y)(3 - (x - 2xy + 4y)) =
     = (x + 2y)(3 - x + 2xy - 4y)
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Применены формулы суммы и разности кубов
c + d = (c + d)(c - cd + d)
c - d = (c - d)(c + cd - d)