Question

Find the sum to indicated terms number of terms in each of the geometric progressions in
$\sqrt{7},\sqrt{21},3\sqrt{7},....n$ terms

Answer 1

common ratio $r=\sqrt{3}$

first term $a=\sqrt{7}$

$\therefore S=\frac{a(r^m-1)}{(r-1)}=\frac{\left(\sqrt{7}\right)\left({\sqrt{3}}^m\right)-1)}{(\sqrt{3}-1)}$