Répondre :
(5x-2)(5x-8)-(3x-5)(x+7)
=25x²-10x-40x+16-(30x²-5x+21x-35)
=25x²-50x+16-30x²-16x+35
=-5x²-66x+51
=25x²-10x-40x+16-(30x²-5x+21x-35)
=25x²-50x+16-30x²-16x+35
=-5x²-66x+51