Let $a$ and $\beta$ be two positive real numbers. For every integer $n > 0$, define $a_n = \int_{\beta}^{n} \frac{a}{u(u^{a}+2+u^{-a})} du$. Then $\lim_{n \to \infty} a_n$ is equal to
(a) $1/(1+\beta^{a})$
(b) $\beta^{a}/(1+\beta^{-a})$
(c) $\beta^{a}/(1+\beta^{a})$
(d) $\beta^{-a}/(1+\beta^{a})$
(a) $1/(1+\beta^{a})$
Let $a$ and $\beta$ be two positive real numbers. For every integer $n > 0$, define $a_n = \int_{\beta}^{n} \frac{a}{u(u^{a}+2+u^{-a})} du$. Then $\lim_{n \to \infty} a_n$ is equal to\\
(a) $1/(1+\beta^{a})$\\
(b) $\beta^{a}/(1+\beta^{-a})$\\
(c) $\beta^{a}/(1+\beta^{a})$\\
(d) $\beta^{-a}/(1+\beta^{a})$