Important Taylor Series

The following are some important Taylor series representations you should memorize. In-tervals of convergence (i.e. intervals on which the representations are valid) are also given.

1

1− x=∞∑

n=0

xn = 1 + x + x3 + x4 + · · · , −1 < x < 1;

ex =∞∑

n=0

xn

n!= 1 + x +

x2

2!+

x3

3!+ · · · , −∞ < x < ∞;

sin x =∞∑

n=0

(−1)n x2n+1

(2n + 1)!= x− x3

3!+

x5

5!− x7

7!+ · · · , −∞ < x < ∞;

cos x =∞∑

n=0

(−1)n x2n

(2n)!= 1− x2

2!+

x4

4!− x6

6!+ · · · , −∞ < x < ∞;

arctan x =∞∑

n=0

(−1)n x2n+1

2n + 1= x− x3

3+

x5

5− x7

7+ · · · , −1 ≤ x ≤ 1;

ln(1− x) =∞∑

n=1

−xn

n= −x− x2

2− x3

3− · · · , −1 < x < 1.