Răspuns:
1)
(a+1)² = a²+2a1+1²
2)
(b-2)² = b²-2b2+2²
3)
(4x-1)(4x+1) = 4x²-1²
4)
(x+y+1)² = x²+y²+c²+2xy+2y1+2x1