We define, for all $x \in \mathbb{R}^{+*}$, $$\Gamma(x) = \int_0^{+\infty} t^{x-1} \mathrm{e}^{-t} \, \mathrm{d}t$$ Justify that we thus define a function on $\mathbb{R}^{+*}$.
We define, for all $x \in \mathbb{R}^{+*}$,
$$\Gamma(x) = \int_0^{+\infty} t^{x-1} \mathrm{e}^{-t} \, \mathrm{d}t$$
Justify that we thus define a function on $\mathbb{R}^{+*}$.