i.3.1.68 Indefinite integrals

condition: Find indefinite integrals. 1) \( \int \frac{x^{4} d x}{x^{2}+1} \) 2) \( \int \frac{x^{3} d x}{\left(x^{2}+2 x-3\right)(x+1)} \); 3) \( \int \sin ^{2} x \cos x d x \)