Question

Help please !!!!!!!!!!

Answer 1

$\boxed{a_1=0.5}\\\\\\a_n=4\cdot a_{n-1}\quad|:a_{n-1}\\\\\\\dfrac{a_n}{a_{n-1}}=4\\\\\\\boxed{r=4}$

so:

$a_n=a_1(r)^{(n-1)}\\\\\boxed{a_n=0.5\cdot4^{(n-1)}}$

Answer C.