The Ratio Test
If
lim
n
®
¥
|a
n+1
|
|a
n
|
= L
<
1 then
¥
å
n = 1
a
n
converges
If
lim
n
®
¥
|a
n+1
|
|a
n
|
= L
>
1 then
¥
å
n = 1
a
n
diverges