\(\int\dfrac{x^3+2x+1}{\left(x+1\right)^2}dx\)
Đặt \(x+1=t\Rightarrow x=t-1;dx=dt\)
\(I=\int\dfrac{\left(t-1\right)^3+2\left(t-1\right)+1}{t^2}dt=\int\dfrac{t^3-3t^2+5t-2}{t^2}dt\)
\(=\int\left(t-3+\dfrac{5}{t}-\dfrac{2}{t^2}\right)dt=\dfrac{1}{2}t^2-3t+5ln\left|t\right|+\dfrac{2}{t}+C\)
\(=\dfrac{1}{2}\left(x+1\right)^2-3\left(x+1\right)+5ln\left|x+1\right|+\dfrac{2}{x+1}+C\)