TeX source:

\begin{align*}\begin{aligned}&D\left(\arctan \left(x^{3}\right)\right)=\frac{1}{1+\left(x^{3}\right)^{2}} D\left(x^{3}\right)=\frac{3 x^{2}}{1+x^{6}} \\&\frac{d}{d x}\left(\arctan \left(e^{x}\right)\right)=\frac{1}{1+\left(e^{x}\right)^{2}} \mathbf{D}\left(e^{x}\right)=\frac{e^{x}}{1+e^{2 x}}\end{aligned}\end{align*}