Cet \( \sum_{\gamma=1}^{n} \frac{y}{(2 k-1)(2 r+1)}=\frac{n^{3}}{A}+\frac{n^{2}}{B}+\frac{5 n}{C}+\frac{f(n)}{D} \) Where \( A, B, C H D \in A \quad 4 f(x) \) is the ratie of two linear polyniniad such that \( \lim _{n \rightarrow \infty} f(n)=\frac{1}{2} \) find \( A \neq B+C+D \).