20. Show that (r) = . (r - 1/2). HINT: (r) = x r-1 e -x dx....

20. Show that Γ(r) = √π. Γ(r - 1/2).

HINT: Γ(r) =

x^r-1e^-x dx. Make the change of variables y = √2x then relate the resulting expression to the normal distribution.