If $\frac{{a + bx}}{{a - bx}} = \frac{{b + cx}}{{b - cx}} = \frac{{c + dx}}{{c - dx}}(x \ne 0)$, then $a,\;b,\;c,\;d$ are in
$A.P.$
$G.P.$
$H.P.$
None of these
If the ratio of two numbers be $9:1$, then the ratio of geometric and harmonic means between them will be
If $a,\;b,\;c$ are in $G.P.$, $a - b,\;c - a,\;b - c$ are in $H.P.$, then $a + 4b + c$ is equal to
The harmonic mean between two numbers is $14\frac{2}{5}$ and the geometric mean $24$ . The greater number them is
If $a + 2b + 3c = 6$, then the greatest value of $abc^2$ is (where $a,b,c$ are positive real numbers)
If all the terms of an $A.P.$ are squared, then new series will be in