Bonjour, pouvez vous m'aider à un exercice de maths svp que je ne comprend pas, merci d'avance de votre aide.

Bonsoir,

(-x - 3)^2 = (-x)^2 + 2 * (-x) * (-3) + (-3)^2
(-x - 3)^2 = x^2 + 6x + 9

x - (-2x + 5)^2 = x - [(-2x)^2 + 2 * -2x * 5 + 5^2)
x - (-2x + 5)^2 = x - (4x^2 - 20x + 25)
x - (-2x + 5)^2 = x - 4x^2 + 20x - 25
x - (-2x + 5)^2 = -4x^2 + 21x - 25

6x - 3 (-x - 1)^2 - (-x + 2)^2 =
(x^2 + 2x + 1) - (x^2 - 4x + 4) =
x^2 + 2x + 1 - x^2 + 4x - 4 =
6x - 3

Factoriser :

(2x + 4)^2 - (x + 2)(x + 3) =
2^2(x + 2)^2 - (x + 2)(x + 3) =
(x + 2)[2(x + 2) - x - 3] =
(x + 2)(2x + 4 - x - 3) =
(x + 2)(x + 1)

x^2 + 2x + 1 - (2x + 2)(x + 3) =
(x + 1)^2 - 2(x + 1)(x + 3) =
(x + 1)(x + 1 - 2(x + 3)) =
(x + 1)(x + 1 - 2x - 6) =
(x + 1)(-x - 5)

4x^2 + 4x + 1 - (6x + 3)(x + 1) =
(2x + 1)^2 - 3(2x + 1)(x + 1) =
(2x + 1)(2x + 1 - 3(x + 1)) =
(2x + 1)(2x + 1 - 3x - 3) =
(2x + 1)(-x - 2)