Question

Find sum of the series $\frac{3}{4},1\frac{1}{2},3,....$ upto $8$ terms.

Answer 1

Clearly the given series is G.P with common ratio $=2$ and $a=\frac{3}{4}$
$S_n$ be sum of first $n$ terms of G.P. and $r$ be common ratio
Formula for sum of $n$ terms of G .P is given by
$S_n=\frac{a(r^n-1)}{r-1}$

$S_8=\frac{\frac{3}{4}\times (2^8-1)}{2-1}=\frac{765}{4}$