I was following a research paper which have the following equation:
$\left(1-\frac{1}{K}\right)^{K-i}\left[1-\left(1-\frac{1-p}{K}\right)^{i}\right]=\frac{i(1-p)}{K}+O\left(\left(\frac{i}{K}\right)^{2}\right)$
Note that the asymptotics are with respect to $K$ and $i$ can vary from 1 to $K$. My understanding of how they obtained it is as follows:
$\left(1-\frac{1}{K}\right)^{K-i} \leq 1-\frac{k-i}{k}+\frac{(k-i)(k-i-1)}{2k^2} \leq \frac{i}{k}+\frac{(k-i)^2}{2k^2}\leq1+O((\frac{i}{k})^2)$.
Similarly, $\left[1-\left(1-\frac{1-p}{K}\right)^{i}\right]\leq \frac{i(1-p)}{K}.$
Are these steps right? Can someone let me know if there are any mistakes in these steps.
