Expressing $\Gamma$(n+$\frac{1}{2}$) for n $\in$ $\mathbb{Z}$ in Factorials

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In summary, the general formula for expressing $\Gamma$(n+$\frac{1}{2}$) for n $\in$ $\mathbb{Z}$ in factorials is $\Gamma$(n+$\frac{1}{2}$) = $\frac{(2n-1)!!}{2^n}\sqrt{\pi}$, derived using properties of the gamma function and the definition of double factorial. This expression is significant for evaluating gamma function at half-integer values and simplifying integrals. Some examples include $\Gamma$(1+$\frac{1}{2}$) = $\frac{1}{2}\sqrt{\pi}$ and $\Gamma$(2+$\frac{1}{2}$) = $\frac{3}{
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Homework Statement



Express [itex]\Gamma (n+\frac{1}{2})[/itex] for [itex]n\in\mathbb{Z}[/itex] in terms of factorials (separately for positive and negative [itex]n[/itex]).

Homework Equations





The Attempt at a Solution



I've got for [itex]n\geqslant 0[/itex] that [tex]\displaystyle \Gamma \left(n+\frac{1}{2} \right) = \frac{(2n-1)!}{2^n} \sqrt{\pi}[/tex] but what do I do when [itex]n<0[/itex] ?
 
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The same thing. Use ##n\Gamma(n)=\Gamma(n+1)##, so ##(-1/2)\Gamma(-1/2) = \Gamma(1/2)## and so on.
 

What is the general formula for expressing $\Gamma$(n+$\frac{1}{2}$) for n $\in$ $\mathbb{Z}$ in factorials?

The general formula for expressing $\Gamma$(n+$\frac{1}{2}$) for n $\in$ $\mathbb{Z}$ in factorials is
$\Gamma$(n+$\frac{1}{2}$) = $\frac{(2n-1)!!}{2^n}\sqrt{\pi}$, where n is a non-negative integer and !! denotes the double factorial function.

How is the formula derived for expressing $\Gamma$(n+$\frac{1}{2}$) in factorials?

The formula for expressing $\Gamma$(n+$\frac{1}{2}$) in factorials is derived using the properties of the gamma function and the definition of the double factorial function. It involves substituting $\frac{1}{2}$ for the variable x in the standard formula for $\Gamma$(x), and then simplifying the resulting expression.

What is the significance of expressing $\Gamma$(n+$\frac{1}{2}$) in factorials?

The expression of $\Gamma$(n+$\frac{1}{2}$) in factorials is significant because it allows for the evaluation of the gamma function at half-integer values, which are commonly encountered in mathematical and scientific problems. It also provides a simplified form for calculating integrals involving the gamma function.

What are some examples of expressing $\Gamma$(n+$\frac{1}{2}$) in factorials?

Examples of expressing $\Gamma$(n+$\frac{1}{2}$) in factorials include:
- $\Gamma$(1+$\frac{1}{2}$) = $\frac{1}{2}\sqrt{\pi}$
- $\Gamma$(2+$\frac{1}{2}$) = $\frac{3}{4}\sqrt{\pi}$
- $\Gamma$(3+$\frac{1}{2}$) = $\frac{15}{8}\sqrt{\pi}$
- $\Gamma$(4+$\frac{1}{2}$) = $\frac{105}{16}\sqrt{\pi}$
and so on.

How is the formula for expressing $\Gamma$(n+$\frac{1}{2}$) in factorials used in real-life applications?

The formula for expressing $\Gamma$(n+$\frac{1}{2}$) in factorials is used in various mathematical and scientific fields, such as probability theory, statistics, and physics. It allows for the calculation of various integrals involving half-integer values, which arise in many real-life problems. Additionally, it is also used in the development of numerical algorithms for computing the gamma function.

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