∫ (2x + 3)/(x² + 2x + 2) dx,注意d(x² + 2x + 2) = (2x + 2) dx= ∫ (2x + 2)/(x² + 2x + 2) dx + ∫ dx/(x² + 2x + 2)= ∫ d(x² + 2x + 2)/(x² + 2x + 2) + ∫ dx/[(x + 1)² + 1],公式∫ dx/(x² + a²) = (1/a)arctan(x/a) + C= ln| x² + 2x + 2 | + arctan(x + 1) + C