A(x) = (2x+3) (x-5) + (3x+7) (2x+3)
factorisation:
(2x+3)(x-5+3x+7)
=(2x+3)(4x+2)
développement:
2x²-10x+6x-15+6x²+9x+14x+21
=8x²+19x+6
B(x) = (5x-1)²-(x-3) (5x-1)
factorisation:
(5x-1)(5x-1-x+3)
=(5x-1)(4x+2)
développement:
25x²-10x+1-(5x²-x-15x+3)
=25x²-10x+1-5x²+x+15x-3
=20x²+16x-2
