i.3.1.56 Indefinite integrals

condition: Calculate the following indefinite integrals: a) \( \int \frac{x d x}{\sqrt{4-x^{2}}} \) b) \( \int \frac{e^{\frac{1}{x}}}{x^{2}} d x \), c) \( \int \frac{2 x-1}{x^{2}-x+1} d x \) d) \( \int \sqrt[3]{x} \ln x d x \)