Question

Which term of $G.P:3-6+12-24+...$ is $-384$?

Answer 1

$\begin{array}{c}a=3r=\frac{-6}{3}=-2\\ a_n=-384\\ a_n=a{r}^{n-1}\\ -384=3{\left(-2\right)}^{n-1}\\ \Rightarrow {\left(-2\right)}^{n-1}=-128\\ \Rightarrow {\left(-2\right)}^{n-1}={\left(-2\right)}^7\\ \Rightarrow n-1=7\\ \Rightarrow =8\end{array}$