12⁢π⁢ⅈ⁢∫c-ⅈ⁢∞c+ⅈ⁢∞Γ⁡(s+a)⁢Γ⁡(b-s)⁢z-s⁢ⅆ⁡s=Γ⁡(a+b)⁢za(1+z)a+b,