Question

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

Answer 1

first term = $\sqrt{7}=a$ and common ratio $=\sqrt{3}=r$

Sum $=\frac{a(r^n-1)}{(r-1)}=\frac{\sqrt{7}({\sqrt{3}}^m-1)}{(\sqrt{3}-1)}$