TeX source:

\begin{aligned} &\mathbf{D}\left(\tan ^{2}(x)+\mathrm{C}\right)=2 \tan ^{1}(x) \mathbf{D}(\tan (x))=2 \tan (x) \sec ^{2}(x) \\ &\mathbf{D}\left(\sec ^{2}(x)+\mathrm{C}\right)=2 \sec ^{1}(x) \mathbf{D}(\sec (x))=2 \sec (x) \sec (x) \tan (x)=2 \tan (x) \sec ^{2}(x) \end{aligned}