Răspuns :
(x+1)² = x² + 2x +1 (formula de calcul prescurtat -binom la patrat )
x² +2x + 1 - 4 = x² + 2x - 3
x² +2x + 1 - 4 = x² + 2x - 3
(x+1)²-4=(x+1)-2²=(x+1-2)(x+1+2)=(x-1)(x+3)
aplicam formula a²-b²=(a-b)(a+b)
aplicam formula a²-b²=(a-b)(a+b)