Fifth term of a $G.P.$ is $2$, then the product of its $9$ terms is
$256$
$512$
$1024$
None of these
If the sum of an infinite $G.P.$ be $9$ and the sum of first two terms be $5$, then the common ratio is
If $A = 1 + {r^z} + {r^{2z}} + {r^{3z}} + .......\infty $, then the value of $r$ will be
If the sum of three terms of $G.P.$ is $19$ and product is $216$, then the common ratio of the series is
If ${\log _x}a,\;{a^{x/2}}$ and ${\log _b}x$ are in $G.P.$, then $x = $
The $G.M.$ of roots of the equation ${x^2} - 18x + 9 = 0$ is