developper

a =2x-4a+2b

b =4abx +2bx²

c =a²x² +6axc +9c²

d = 4a²x² -b²

e =4ax -6ab-8x²+12bx

factoriser

f = bx(x-1)

g =a(y-x)

h =(ax+b)²

i =(2xy-7)(2xy+7)

j =(2x-a-2x-a)(2x-a+2x+a) =-2a(4x)