a) x²-2x+1-y² =
=(x-1)²-y² =
=(x-1-y) (x-1+y)
b) x²-4y²+6x+9=
=(x+3)²-4y²=
=(x+3-2y)(x+3+2y)
c) 16x²-16y²-8x+1=
= (4x-1)²-16y²=
= (4x-1-4y)(4x-1+4y)
d) 4x²-9y²+6y-1=
=4x²-(3y-1)²=
=(2x-3y+1)(2x+3y-1)
e) x²-y²-4yz-4z²=
=x²-(y²+4yz+4z²)=
=x²-(y+2z)²=
=(x-y-2z)(x+y+2z)
