Kết quả ko làm tròn nhé
\(S=\int\limits^2_1\frac{1}{x\left(x^3+1\right)}dx=\int\limits^2_1\frac{1}{x}dx-\frac{1}{3}\int\limits^2_1\frac{1}{x+1}dx+\frac{1}{3}\int\limits^2_1\frac{-2x+1}{x^2-x+1}dx+\frac{2}{3}\int\limits^2\frac{dx}{x^2-x+1}\\ =lnx|^2_1-\frac{1}{3}ln\left(x+1\right)|^2_1-\frac{1}{3}ln\left(x^2-x+1\right)|^2_1+\frac{2}{3}\int\limits^2\frac{dx}{x^2-x+1}\\ =\frac{4}{3}ln2-\frac{2}{3}ln3\)