Find the harmonic mean of $a/b$ and $b/a$.

If $\log_a x, \log_b x, \log_c x$ are in $H.P.$,then $a, b, c$ are in

Let $a_1, a_2, a_3, \ldots$ be in harmonic progression with $a_1 = 5$ and $a_{20} = 25$. The least positive integer $n$ for which $a_n < 0$ is

If $\ln(a+c), \ln(c-a), \ln(a-2b+c)$ are in $A.P.$,then

If $H$ is the harmonic mean between $a$ and $b$,then what is the value of $\frac{1}{H - a} + \frac{1}{H - b}$?

In a $H.P.$,the $p^{th}$ term is $q$ and the $q^{th}$ term is $p$. Then the $(pq)^{th}$ term is