\(\mathrm{dI}=\sigma 2 \pi \mathrm{r}\) dr \(\mathrm{r}^{2}\)
\(\mathrm{dI}=2 \pi(\mathrm{A}+\mathrm{Br}) \mathrm{r}^{3} \mathrm{dr}\)
\(\int \mathrm{dI}=2 \pi \int_{0}^{\mathrm{a}}\left(\mathrm{Ar}^{3}+\mathrm{Br}^{4}\right) \mathrm{dr}\)
\(I=2 \pi a^{4}\left(\frac{A}{4}+\frac{B a}{5}\right)\)