## Algebra 2 (1st Edition)

$2r^2\pi+2\frac{100}{r}$
We know that the surface of a cylinder can be obtained by: $S=2r^2\pi+2\pi rl$, from part a): $l=\frac{100}{r^2\pi}$, hence: $S=2r^2\pi+2\pi r\frac{100}{r^2\pi}=2r^2\pi+2\frac{100}{r}$