Répondre :
A= (X - 3 ) (X + 7) -- (2X - 7 ) (X-3)
=(x-3)(-x+14)
=-x²+17x-42
B = (2X - 1) ( X - 8) + (X - 8 )²
=(x-8)(3x-9)
=3x²-33x+72
C = (2X + 3)² -- (7 - 4X)²
=(-2x+10)(6x-4)
=-12x²+68x-40
=(x-3)(-x+14)
=-x²+17x-42
B = (2X - 1) ( X - 8) + (X - 8 )²
=(x-8)(3x-9)
=3x²-33x+72
C = (2X + 3)² -- (7 - 4X)²
=(-2x+10)(6x-4)
=-12x²+68x-40