QuestionFind the intervals on which $f(x)$ is increasing, the intervals on which $f(x)$ is decreasing, and the local extrema. $$f(x)=x^{3}+2 x+1$$
Find $f^{\prime}(x)$. $$\begin{array}{l} f(x)=x^{3}+2 x+1 \\ f^{\prime}(x)=\square \end{array}$$