9.3.1.4 Indefinite integrals

Problem: Let's calculate the integral: 1) \( \int \frac{d x}{\sqrt{5-x^{2}}} \), 2) \( \int \frac{x+23}{x^{2}+x-20} d x \), 3) \( \int x e^{-7 x} d x \).