Biểu thức (4 – x^2) (x^2 + 2x − 3) (x^2 + 5x + 9) âm khi

x ∈ (1; 2).

x ∈ (−3; −2) ∪ (1; 2).

x ≥ 4.

x ∈ (−∞; −3) ∪ (−2; 1) ∪ (2; +∞).