Question

Calculate the $7^{th}$ term in the G.P. $1,-3,9,-\mathrm{27...}$

• A. $429$
• B. $529$
• C. $629$
• D. $729$

Answer 1

The correct option is D $729$

We know the formula,

$t_n=a{r}^{n-1}$

Here $n=7$

Common ratio $=-3$ and $a=1$

$t_7=1\times (-3{)}^{7-1}$

$t_7=1\times (-3{)}^6$

$t_7=729$