Exercice 9: Factoriser:
a) A(x) = 5x² + 25x
b) B(x) = 3x + 9
c) C(x) = (x-4) (2x + 1) + (x-4) (3x - 2)
d) D(x) = (2x + 1)(x-4) - (2x + 1)(2x - 3)
e) E(x) = 2x(x + 3) - 4x²(x+3)(2x + 1)