Répondre :
-(a-7)(3a+2)-(2x-3)²
-(3a²+2a-21a-14)-(4x²-12x+9)
(-3a²-2a+21a+14)-(4x²-12x+9)
-3a²+19a+14-4x²+12x-9
-3a²-4x²+19a+12x+5
-(3a²+2a-21a-14)-(4x²-12x+9)
(-3a²-2a+21a+14)-(4x²-12x+9)
-3a²+19a+14-4x²+12x-9
-3a²-4x²+19a+12x+5