Suppose the sides of a triangle form a geometric progression with common ratio $r$. Then, $r$ lies in the interval
$\left(0, \frac{-1+\sqrt{5}}{2}\right)$
$\left(\frac{1+\sqrt{5}}{2}, \frac{2+\sqrt{5}}{2}\right)$
$\left(\frac{1+\sqrt{5}}{2}, \frac{2+\sqrt{5}}{2}\right]$
$\left(\frac{2+\sqrt{5}}{2}, \infty\right)$
Find the sum of the sequence $7,77,777,7777, \ldots$ to $n$ terms.
The sum to infinity of the following series $2 + \frac{1}{2} + \frac{1}{3} + \frac{1}{{{2^2}}} + \frac{1}{{{3^2}}} + \frac{1}{{{2^3}}} + \frac{1}{{{3^3}}} + ........$, will be
Let $a_{1}, a_{2}, a_{3}, \ldots$ be a G.P. such that $a_{1}<0$; $a_{1}+a_{2}=4$ and $a_{3}+a_{4}=16 .$ If $\sum\limits_{i=1}^{9} a_{i}=4 \lambda,$ then $\lambda$ is equal to
The value of ${a^{{{\log }_b}x}}$, where $a = 0.2,\;b = \sqrt 5 ,\;x = \frac{1}{4} + \frac{1}{8} + \frac{1}{{16}} + .........$to $\infty $ is
The sum of the first five terms of the series $3 + 4\frac{1}{2} + 6\frac{3}{4} + ......$ will be