3
The Integral and Comparison Tests; Estimating Sums
In general, it is difficult to find the exact sum of a series. We
were able to accomplish this for geometric series and the
series 1/[n(n + 1)] because in each of those cases we
could find a simple formula for the nth partial sum s
n
.
But usually it isn’t easy to compute lim
n→
s
n
.
Therefore in this section we develop tests that enable us to
determine whether a series is convergent or divergent
without explicitly finding its sum.