If $\frac{1}{{b - c}},\;\frac{1}{{c - a}},\;\frac{1}{{a - b}}$ be consecutive terms of an $A.P.$, then ${(b - c)^2},\;{(c - a)^2},\;{(a - b)^2}$ will be in
$G.P.$
$A.P.$
$H.P.$
None of these
If the sum of the first $2n$ terms of $2,\,5,\,8...$ is equal to the sum of the first $n$ terms of $57,\,59,\,61...$, then $n$ is equal to
Find the sum of all natural numbers lying between $100$ and $1000,$ which are multiples of $5 .$
If $\frac{a}{b},\frac{b}{c},\frac{c}{a}$ are in $H.P.$, then
If twice the $11^{th}$ term of an $A.P.$ is equal to $7$ times of its $21^{st}$ term, then its $25^{th}$ term is equal to