TeX source:

\sum_{k=1}^{10}\left(k^{3}+k\right)=\sum_{k=1}^{10} \mathrm{k}^{3}+\sum_{k=1}^{10} \mathrm{k}=\left(\frac{10(11)}{2}\right)^{2}+\frac{10(11)}{2}=(55)^{2}+55=3080