T
n
(
x
)
=
1
+
x
+
x
2
2!
+
x
3
3!
+
...
+
x
n
n
!
=
n
∑
k
=
0
x
k
k
!
lim
n
→
∞
T
n
(
x
)
=
e
x
⬃
