Răspuns :
a)x⁴-x³-x-1=(x²)²-1-x³-x
Folosim formula a²-b²=(a-b)(a+b)
(x²-1)(x²+1)-x(x²+1)=(x²+1)(x²-1-x)
Folosim formula a²-b²=(a-b)(a+b)
(x²-1)(x²+1)-x(x²+1)=(x²+1)(x²-1-x)