Salut !
A = (x-2)²+4(x-2)(x+5)
= (x-2)(x-2)+4(x-2)(x+5)
= (x-2)[(x-2)+4(x+5)]
= (x-2)(x-2+4x+20)
= (x-2)(5x+18)
B = (2a-1)²-9 = (2a-1)²-3²
=(2a-1+3)(2a-1-3)
= (2a+2)(2a-4)
D = x(1-x)+(x-1)(x+2)
= (x)(-(1-x)+(x-1)(x+2)
= -x(x-1)+(x-1)(x+2)
= (x-1)[-x+x+2)
= (x-1)(2)
= 2(x-1)
E = (x-1)²-2(x-1)+1
= (x-1)(x-1)-2(x-1)+1
= (x-1)[(x-1-2)]+1
= (x-1)(x-3)+1