x → ∞ lim x Γ ( 1 8 0 x 1 ) Γ ( 1 − 1 8 0 x 1 ) = ?
Notation: Γ ( ⋅ ) denotes the gamma function .
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That's a cool way.
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I'm from WB, close to your place, isn't it? :D
Similar solution as @Alak Bhattacharya 's just with more details for the better understanding of some.
L = x → ∞ lim x Γ ( 1 8 0 x 1 ) Γ ( 1 − 1 8 0 x 1 ) = x → ∞ lim x sin 1 8 0 x π π = x → ∞ lim sin 1 8 0 x π 1 8 0 ⋅ 1 8 0 x π = 1 8 0 By Euler’s reflection equation: Γ ( z ) Γ ( 1 − z ) = sin ( π z ) π Note that u → 0 lim u sin u = 1
Reference: Euler's reflection formula
The first point to notice that we can use the reflection equation .Then we get π/sin(1/x) if we measure it in degrees.Then since limit as x approaches infinity sin(1/x)=π/(180x) .Then inputting it to the π/sin(1/x) yields gives 180x , dividing both side by x gives our answer as 180. (We can show that sin(1/x) is approximately π/(180x), when measured in degrees ,by Maclaurin series)
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We know that Γ ( 1 8 0 x 1 ) Γ ( 1 − 1 8 0 x 1 ) = sin ( 1 8 0 x π ) π .
Changing x to h = x 1 , we get the required limit as
1 8 0 π π h → 0 lim sin ( 1 8 0 π h ) 1 8 0 π h
= 1 8 0 × 1 = 1 8 0 .