9.3.1.2 Indefinite integrals

Problem: Calculate the integral: 1) \( \int \frac{d x}{(x-1)^{2}(x-2)} \), 2) \( \int \cos \frac{x}{2} \cos \frac{x}{3} d x \), 3) \( \int \frac{\sqrt[6]{x}+1}{\sqrt[6]{x^{7}}+\sqrt[4]{x^{5}}} d x \).