PlanetMath (more info)
 Math for the people, by the people.
Encyclopedia | Requests | Forums | Docs | Wiki | Random | RSS  
Login
create new user
name:
pass:
forget your password?
Main Menu
Owner confidence rating: High Entry average rating: No information on entry rating
binomial formula (Theorem)

The binomial formula gives the power series expansion of the $ p^{\text{th}}$ power function. The power $ p$ can be an integer, rational, real, or even a complex number. The formula is

$\displaystyle (1+x)^p$ $\displaystyle = \sum_{n=0}^\infty \frac{p^{\underline{n}}}{n!} \, x^n$    
  $\displaystyle = \sum_{n=0}^\infty \binom{p}{n} x^n$    

where $ p^{\underline{n}}= p(p-1)\ldots (p-n+1)$ denotes the falling factorial, and where $ \binom{p}{n}$ denotes the generalized binomial coefficient.

For $ p=0,1,2,\ldots$ the power series reduces to a polynomial, and we obtain the usual binomial theorem. For other values of $ p$, the radius of convergence of the series is $ 1$; the right-hand series converges pointwise for all complex $ \vert x\vert<1$ to the value on the left side. Also note that the binomial formula is valid at $ x=\pm 1$, but for certain values of $ p$ only. Of course, we have convergence if $ p$ is a natural number. Furthermore, for $ x=1$ and real $ p$, we have absolute convergence if $ p>0$, and conditional convergence if $ -1<p<0$. For $ x=-1$ we have absolute convergence for $ p>0$.



"binomial formula" is owned by rmilson.
(view preamble)

View style:

See Also: binomial theorem, generalized binomial coefficients

Other names:  Newton's binomial series

Attachments:
proof of binomial formula (Proof) by rmilson
binomial formula for negative integer powers (Corollary) by rspuzio
Log in to rate this entry.
(view current ratings)

Cross-references: conditional convergence, absolute convergence, natural number, side, complex, pointwise, converges, series, radius of convergence, binomial theorem, polynomial, generalized binomial coefficient, falling factorial, complex number, even, real, rational, integer, power, power function, power series
There are 11 references to this entry.

This is version 8 of binomial formula, born on 2002-02-19, modified 2006-03-19.
Object id is 2204, canonical name is BinomialFormula.
Accessed 26910 times total.

Classification:
AMS MSC26A06 (Real functions :: Functions of one variable :: One-variable calculus)

Pending Errata and Addenda
None.
[ View all 1 ]
Discussion
Style: Expand: Order:
forum policy

No messages.

Interact
post | correct | update request | prove | add result | add corollary | add example | add (any)