Answer
Determine $r=\dfrac{a_{k+1}}{a_k}$
Compare $r$ to 1
Work Step by Step
When $\sum a_k$ is an infinite series of positive terms, in order to apply the Ratio Test we determine $r=\lim\limits_{k \to \infty} \dfrac{a_{k+1}}{a_k}$.
Then we compare $r$ with 1 to decide if the series converges, diverges or the test is inconclusive:
- if $0\leq r<1$ the series converges
- if $r>1$ the series diverges
- if $r=1$ the test is inconclusive.
