Bonjour
A = (x-2)(x-2+4x+20)
A = (x-2)(5x+18)
B = (2a-1-3)(2a-1+3)
B = (2a-4)(2a+2)
B = 4(a-2)(a+1)
C = (x+5-2x-7)(x+5+2x+7)
C = (-x-2)(3x+12)
C = 3(-x-2)(x+4)
D = x(1-x) - (1-x)(x+2)
D =(1-x)(x-x-2)
D = (1-x) (-2)
D = -2(1-x)
E = x^2 -2x +1 -2x+2 + 1
E = x^2 -4x +4
E = (x-2)^2