Thus, this is the Maclaurin series for . If we change the variable from to we get

the Maclaurin Series expansion for . (Note that to find Maclaurin Series
directly requires some tedious derivative computations). Now for using
theorem 27.1.8, we have
.
Since for , , we have . Hence

In fact, using the alternative series test, it is easy to see that the above holds for also. |