(4x-3y)²-16y²
=(4x-3y+4y)(4x-3y-4y)
=(4x+y)(4x-7y)
x²+2x(y-z)+(z-y)²
=x²+2x(y-z)+(y-z)²
=[x+(y-z)]²
=(x+y-z)²
(a²-a)²-(a-1)²
=a²(a-1)²-(a-1)²
=(a-1)²(a²-1)
=(a-1)³(a+1)