Développer et réduire, svp de l'aide A = (3 x + 2)(5x – 3) + (6x + 7)(x +3) B = (x – 3) (5x + 7) – (2 – x) (6 – x) C = (2x – 5) (x – 4) – ( x – 4) (3 x + 7)

A = 15x²-9x+10x-6+6x²+18x+7x+21
A= 21x²+26x+15

B= 5x²+7x-15x-21-(12-2x-6x+x²)
B=5x²+8x-21-12+2x+6x-x²
B= 4x²+16x-33

C= 2x²-8x-5x+20-(3x²+7x-12x-28)
C= 2x²-8x-5x+20-3x²-7x+12x+28
C= -x²-8x+48

fait 2 fois la double distributivité.
tel que:
A= (3x x 5x + 3x x -3) + (2 x 5x + 2 x -3)
  = (15xCarré + (-3x)) + (10x + (-6))
  = 15xCarré + (-3x + 10x) + (-6)
  = 15xCarré + 7x -6