i.3.1.67 Indefinite integrals

condition: Integrate rational functions. 1) \( \int \frac{d x}{x^{3}+3 x^{2}+2 x} \); 2) \( \int \frac{d x}{x^{3}+x} \) 3) \( \int \frac{(x+3) d x}{x(x+1)(x+2)} \).