\(\frac{1}{{{k_{eq}}}} = \frac{1}{{{k_1}}} + \frac{1}{{{k_2}}}\)\( = \frac{L}{{YA}} + \frac{1}{k}\) \(\Rightarrow\) \(k_{eq} = {\frac{{KYA}}{{KL+YA}}} \)
\(\therefore \) \(T = 2\pi \sqrt {\frac{m}{{{k_{eq}}}}} = \,2\pi \sqrt {\frac{{m(kL + YA)}}{{kYA}}} \)