Definition: Maclaurin Series

The Maclaurin series of a function ff that is infinitely differentiable at 00 is its Taylor series centered at c=0c = 0:

∑n=0∞f(n)(0)n!xn=f(0)+f′(0)x+f′′(0)2!x2+f′′′(0)3!x3+⋯ .\sum_{n=0}^{\infty} \frac{f^{(n)}(0)}{n!} x^n = f(0) + f'(0)x + \frac{f''(0)}{2!}x^2 + \frac{f'''(0)}{3!}x^3 + \cdots.

Several elementary functions have Maclaurin series that converge to the function for all real xx:

ex=∑n=0∞xnn!,sin⁡x=∑n=0∞(−1)nx2n+1(2n+1)!,cos⁡x=∑n=0∞(−1)nx2n(2n)!,e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!}, \qquad \sin x = \sum_{n=0}^{\infty} \frac{(-1)^n x^{2n+1}}{(2n+1)!}, \qquad \cos x = \sum_{n=0}^{\infty} \frac{(-1)^n x^{2n}}{(2n)!}, 11−x=∑n=0∞xn(∣x∣<1),ln⁡(1+x)=∑n=1∞(−1)n−1nxn(−1<x≤1).\frac{1}{1-x} = \sum_{n=0}^{\infty} x^n \quad (|x| < 1), \qquad \ln(1+x) = \sum_{n=1}^{\infty} \frac{(-1)^{n-1}}{n} x^n \quad (-1 < x \le 1).
10 viewsMathematics · Single Variable Calculus
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