If $m$ is the $A.M$ of two distinct real numbers $ l$ and $n (l,n>1) $ and $G_1, G_2$ and $G_3$ are three geometric means between $l$ and $n$ then $G_1^4 + 2G_2^4 + G_3^4$ equals :
$4{l^2}{m^2}{n^2}$
$4{l^2}mn$
$4l{m^2}n$
$4lm{n^2}$
Let $G$ be the geometric mean of two positive numbers $a$ and $b,$ and $M$ be the arithmetic mean of $\frac {1}{a}$ and $\frac {1}{b}$. If $\frac {1}{M}\,:\,G$ is $4:5,$ then $a:b$ can be
If $A . M$. and $G M$. of two positive numbers $a$ and $b$ are $10$ and $8 , $ respectively, find the numbers.
If all roots of the equation $x^3 -2ax^2 + 3bx -8$=$0$ are positive, $a$,$b \in R$ , then the minimum value of $b$ is
If $a,\,b,\;c$ are in $A.P.$ and ${a^2},\;{b^2},\;{c^2}$ are in $H.P.$, then
Two sequences $\{ {t_n}\} $ and $\{ {s_n}\} $ are defined by ${t_n} = \log \left( {\frac{{{5^{n + 1}}}}{{{3^{n - 1}}}}} \right)\,,\,\,{s_n} = {\left[ {\log \left( {\frac{5}{3}} \right)} \right]^n}$, then