教科書基本レベル
$$\begin{align*}\int\frac{x^{2}+3x+1}{x-1}dx & =\int\frac{(x-1)(x+4)+5}{x-1}dx\\& =\int\left(x+4+\frac{5}{x-1}\right)dx\\& =\frac{1}{2}x^{2}+4x+5\log\left|x-1\right|+C\end{align*}$$
教科書基本レベル
$$\begin{align*}\int\frac{x^{2}+3x+1}{x-1}dx & =\int\frac{(x-1)(x+4)+5}{x-1}dx\\& =\int\left(x+4+\frac{5}{x-1}\right)dx\\& =\frac{1}{2}x^{2}+4x+5\log\left|x-1\right|+C\end{align*}$$