For the geometric series $a + ar + ar^2 + \ldots$ with $r
e 1$, the partial sum up to $n$-th term is —

Question

For the geometric series $a + ar + ar^2 + \ldots$ with $r 
e 1$, the partial sum up to $n$-th term is —

Accepted Answer

$a \cdot \dfrac{1 - r^n}{1 - r}$

Answer

$a \cdot \dfrac{1 + r^n}{1 + r}$

Answer

$a \cdot \dfrac{r^n - 1}{r}$

Answer

$\dfrac{a}{1 - r}$

For the geometric series a+ar+ar2+…a + ar + ar^2 + \ldotsa+ar+ar2+… with r≠1r \ne 1r=1, the partial sum up to nnn-th term is —