Răspuns:
a)
(x - 2)^2 - (2x + 1)^2 ==
(x - 2 - 2x - 1)(x - 2 + 2x + 1) =
(- 3x - 3)(3x - 1)
b)
x^2 + 10x + 25 =
x^2 + 5x + 5x + 25 =
x (x + 5) + 5 (x + 5) =
(x + 5)(x + 5)
c)
x^2 + 8x + 12 =
x^2 + 2x + 6x + 12 =
x (x + 2) + 6 (x + 2) =
(x + 2)(x + 6)
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