P = n = 1 ∏ ∞ n + 1 1 n e n 1 1
If P denotes the above product, evaluate ⌊ P ⌋ .
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I think you need to explain how you are going from H n − ln ( n + k ) for k = 1 , . . 1 1 to simply H n − ln ( n ) ... that's the key step.
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but isnt the n → ∞ lim ln ( n ) = n → ∞ lim ln ( n + k ) ?
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Well, both of these limits are infinity, so, that does not prove much...
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@Otto Bretscher – hmm.... in another way, n → ∞ lim ( H n − ln ( n + 1 ) ) = n → ∞ lim ( H n + 1 − ln ( n + 1 ) ) = γ this is beacause n → ∞ lim n 1 = 0 Does this serve as a good proof?
The best way to see this is to observe that the partial product is ( n + 1 1 ) ! 1 1 ! n ! n 1 1 e 1 1 ( H n − ln n ) = 1 1 ! ( n + 1 ) ( n + 2 ) ⋯ ( n + 1 1 ) n 1 1 e 1 1 ( H n − ln n ) The fraction, being equal to r = 1 ∏ 1 1 ( 1 + n r ) − 1 certainly tends to 1 as n → ∞ , and H n − ln n → γ as n → ∞ . Hence the result.
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Yes, that's a good explanation! I realized that Aareyan's solution wasn't quite complete, but I did not want to bother him any longer ;)
i did exactly the same thing. i did not get the correct answer. very strange may be because i have taken euler maschoroni constant to be 0.57721.
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Not really. The answer contains 1 1 significant tigures, and you are using a value of γ with only 5 SF.
exactly. i missed it. thanks.
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we split the product into 2 parts, let e x p ( x ) = e x , H n = k = 1 ∑ n k 1 .the product can be written as n → ∞ lim k = 1 ∏ n k + 1 1 k k = 1 ∏ n e x p ( k 1 1 ) The first product is just a basic telescoping series - product . the second one can be evaluated using the rules of exponents . = n → ∞ lim ( n + 1 ) ( n + 2 ) . . . ( n + 1 1 ) 1 1 ! e x p ( k = 1 ∑ n n 1 1 ) = n → ∞ lim ( n + 1 ) ( n + 2 ) . . . ( n + 1 1 ) 1 1 ! e x p ( 1 1 H n ) we know as n tends towards infinity, so does the harmonic series! But subtracting the log of n from it is finite! This motivates us to write this as n → ∞ lim 1 1 ! e x p ( 1 1 H n − ln ( ( n + 1 ) ( n + 2 ) . . . ( n + 1 1 ) ) ) ) = n → ∞ lim 1 1 ! e x p ( ( H n − ln ( n + 1 ) ) + ( H n − ln ( n + 2 ) ) + . . . ( H n − ln ( n + 1 1 ) ) ) ) Remember n → ∞ lim ( H n − ln ( n ) ) = γ ≈ . 5 7 7 2 we can also say n → ∞ lim ( H n − ln ( n + 1 ) ) = n → ∞ lim ( H n + 1 − ln ( n + 1 ) ) = γ this is beacause n → ∞ lim n 1 = 0 so, it becomes 1 1 ! e x p ( 1 1 γ ) ≈ 2 2 8 3 7 7 3 7 5 3 7