Subiectul al III-lea, 2. c)

c) ∫₋₁¹ x f(x) dx = 2∫₋₁¹ x² arctg x dx = 2∫₁⁻¹ (−x)² arctg(−x)(−1) dx = −2∫₋₁¹ x² arctg x dx = −∫₋₁¹ x f(x) dx - 3p 2∫₋₁¹ x f(x) dx = 0, deci ∫₋₁¹ x f(x) dx = 0 - 2p