# What is the common ratio in this geometric sequence 4, 16, 64, 256, 1024, ...?

Nov 8, 2015

$r = 4$

#### Explanation:

${A}_{n} = {A}_{1} {r}^{n - 1}$

${A}_{1} = 4$

${A}_{2} = {A}_{1} {r}^{2 - 1} = {A}_{1} r = 16$

$\implies 4 r = 16$
$\implies r = 4$