Réponse détaillée !!

A(x)=(2x-3)(-7x+5)
      =-14x+10x+21x-15
      = 17x-15

B(x)= (8x+3)²-(7x-5)²
      = (8x+3)(8x+3)-(7x-5)(7x-5)
       =64x²+24x+24x+9-(49x²-35x-35x+25)
       =64x²+48x+9-49x²+70x-25
       =15x²+118x-16

C(x)= (2x-7)(5x+4)+(2x-7)(8x-3)
      = (2x-7)(13x+1)

D(x) = (5x-7)²