what is r-2/k-9/r^2/k^2 ?
\(r-\frac{2}{k}-\frac{9}{r^2}\div k^2\\ =r-\frac{2}{k}-\frac{9}{r^2k^2}\\ or\\ =\frac{r^3k^2-2r^2k-9}{r^2k^2}\\ \)
