Răspuns:
Explicație pas cu pas:
(x²-1)(x+1) ≥ 0 <=> (x-1)(x+1)(x+1) ≥ 0 <=>
(x+1)²(x-1) ≥ 0
(x+1)² ≥ 0 , oricare x ∈ R
x I -∞ -1 1 +∞
(x+1)² I ++++++++++0+++++++++++++++++++
(x-1) I--------------------------------0+++++++++++
(x+1)²(x-1) I------------------0------------0+++++++++++
=> x ∈ [1 , +∞) ∪ {-1}