# Maclaurin Series Formula

A Maclaurin series is a function that has expansion series that gives the sum of derivatives of that function. The Maclaurin series of a function $f(x)$ up to order n may be found using Series $[f, {x, 0, n}]$.

It is a special case of Taylor series when x = 0. The Maclaurin series is given by

$\large f(x)=f(x_{0})+{f}'(x_{0})(x-x_{0})+\frac{{f}”(x_{0})}{2!}(x-x_{0})^{2}+\frac{{f}”'(x_{0})}{3!}(x-x_{0})^{3}+…..$

The Maclaurin series formula is

$\large f(x)=\sum_{n=0}^{\infty}\frac{f^{n}(x_{0})}{n!}(x-x_{0})$

Where,
f(xo), f’(xo), f’‘(xo)……. are the successive differentials when xo = 0.

 Function Maclaurin Series $e^{x}$ $\sum_{k=0}^{\infty}=1+x+\frac{x^{2}}{2!}+\frac{x^{3}}{3!}+\frac{x^{4}}{4!}+…..$ $sin\;x$ $\sum_{k=0}^{\infty}(-1)^{2}=\frac{x^{2k+1}}{(2k+1)!}=x-\frac{x^{3}}{3!}+\frac{x^{5}}{5!}+\frac{x^{7}}{7!}+…..$ $cos\;x$ $\sum_{k=0}^{\infty}(-1)^{2}=\frac{x^{2k}}{(2k)!}=1-\frac{x^{2}}{2!}+\frac{x^{4}}{4!}+\frac{x^{6}}{6!}+…..$ $\frac{1}{1-x}$ $\sum_{k=0}^{\infty}x^{k}=1+x+x^{2}+x^{3}+….(if-1 ### Solved Examples Question 1: Expanding$e^{x}$: Find the Maclaurin Series expansion of$f(x)=e^{x}$Solution: Recalling that the derivative of the exponential function is${f}'(x)=e^{x}$In fact, all the derivatives are$e^{x}$.${f}'(0)=e^{0}=1{f}”(0)=e^{0}=1{f}”'(0)=e^{0}=1$We see that all the derivatives, when evaluated at x = 0, give us the value 1. Also, f(0)=1, so we can conclude the Maclaurin Series expansion will be simply:$e^{x}\approx 1+x+\frac{1}{2}x^{2}+\frac{1}{6}x^{3}+\frac{1}{24}x^{4}+\frac{1}{120}x^{5}+….\$

#### Practise This Question

The molar mass of Z is 20 gms. Find the mass of 1 atom of Z.