If $\frac{{x + y}}{2},\;y,\;\frac{{y + z}}{2}$ are in $H.P.$, then $x,\;y,\;z$ are in
$A.P.$
$G.P.$
$H.P.$
None of these
If $y = x - {x^2} + {x^3} - {x^4} + ......\infty $, then value of $x$ will be
If $a,\;b,\;c$ are in $A.P.$, then ${3^a},\;{3^b},\;{3^c}$ shall be in
The sum of a $G.P.$ with common ratio $3$ is $364$, and last term is $243$, then the number of terms is
If the sum of $n$ terms of a $G.P.$ is $255$ and ${n^{th}}$ terms is $128$ and common ratio is $2$, then first term will be
$0.\mathop {423}\limits^{\,\,\,\,\, \bullet \, \bullet \,} = $