bonjour voila je n'arrive pas l'exercice 4 merci a vous

Salut :)

Exercice n°4 :

1) Développer et réduire :
A = (2x - 3)(3 - x) + (x + 4)(x - 5)
A = 2x x 3 + 2x x (-x) - 3 x 3 - 3 x (-x) + (x) x (x) + (x) x (-5) + 4 x (x) + 4 x (-5)
A = 6x + -2x² - 9 + 3x + x² - 5x + 4x - 20
A = -x² + 8x - 29

B = (-3x + 1)(2x - 5) - (3x + 1)(-2x + 7)
B = -3x x 2x - 3x x (-5) + 1 x 2x + 1 x (-5) - (3x x (-2x) + 3x x 7 + 1 x (-2x) + 1 x 7
B = -6x² + 15x + 2x - 5 - (-6x² + 21x  - 2x + 7)
B = -6x² + 15x + 2x - 5 + 6x² - 21x + 2x - 7
B = -2x - 12

2) Factoriser :
C = (x - 3)(4x - 1) + (x - 3)(4x + 1)
C = (x - 3)[(4x - 1) + (4x + 1)]
C = (8x)(x - 3)

D = (4x - 5)(x - 3) - (-3x - 1)(4x - 5)
D = (4x - 5)[(x - 3) - (-3x - 1)]
D = (4x - 5)(x - 3 + 3x + 1)
D = (4x - 5)(4x - 2)

J'espère t'avoir aidé(e)! ^^

A=(2x-3)(3-x)+(x+4)(x-5)
=6x-2x² -9+3x +x²-5x+4x-20
=-x² + 8x-29.
B =(-3x+1)(2x-5) -(-3x+1)(-2x+7)
= (-3x+1)(2x-5+2x-7)
=(-3x+1) (4x-12)
=-12x²+36x+4x-12
=-12x² +40x-12