Being Inspired is Awesome!

Calculus Level 5

N = m = 0 2 2 5 1 ( 1 + 1 n = 1 5 ( m + 2 2 n + m 2 n ) ) \large\color{#0C6AC7}{\mathfrak{N}}=\displaystyle\sum_{m=0}^{2^{2^{5}}-1} \left( \dfrac{1+1}{\displaystyle\prod_{n=1}^{5}\left(\sqrt[2^n]{m+2}+\sqrt[2^n]{m}\right)}\right)

log 2 ( log 2 ( ( N 1 ) 2 5 1 ) ) + 4 = ? \large\log_2\left(\log_{2}\left((\color{#0C6AC7}{\mathfrak{N}}-1)^{2^5}-1\right)\right)+4=\, ?


Inspired by Svatejas Shivakumar.


The answer is 9.

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1 solution

Rishabh Jain
Apr 23, 2016

Inspiration 1 n = 1 5 ( m + 2 2 n + m 2 n ) \dfrac{1}{\displaystyle\prod_{n=1}^{5}\left(\sqrt[2^n]{m+2}+\sqrt[2^n]{m}\right)} = ( m + 2 2 5 m 2 5 ) ( n = 1 4 ( m + 2 2 n + m 2 n ) ) ( ( m + 2 2 5 + m 2 5 ) ( m + 2 2 5 m 2 5 ) ) ( m + 2 2 4 m 2 4 ) =\dfrac{\color{#D61F06}{(\sqrt[2^5]{m+2}-\sqrt[2^5]{m})}}{\left(\displaystyle\prod_{n=1}^{4}\left(\sqrt[2^n]{m+2}+\sqrt[2^n]{m}\right)\right)\underbrace{\left((\sqrt[2^5]{m+2}+\sqrt[2^5]{m})(\color{#D61F06}{\sqrt[2^5]{m+2}-\sqrt[2^5]{m})}\right)}_{\large(\sqrt[2^4]{m+2}-\sqrt[2^4]{m})}} Using ( a + b ) ( a b ) = a 2 b 2 \color{teal}{(a+b)(a-b)=a^2-b^2} repeatedly we get: N = n = 0 2 2 5 1 ( m + 2 2 5 m 2 5 ) \large\color{#0C6AC7}{\mathfrak{N}}=\displaystyle\sum_{n=0}^{2^{2^5}-1}\left(\sqrt[2^5]{m+2}-\sqrt[2^5]{m} \right) ( A T e l e s c o p i c S e r i e s ) \mathbf{(A~Telescopic~Series)} = 0 1 + 2 2 5 2 5 + 2 2 5 + 1 2 5 =-0-1+\sqrt[2^5]{2^{2^5}}+\sqrt[2^5]{2^{2^5}+1} = 1 + 2 2 5 + 1 2 5 =1+\sqrt[2^5]{2^{2^5}+1} log 2 ( log 2 ( ( N 1 ) 2 5 1 ) ) + 4 \large\log_2\left(\log_{2}\left((\color{#0C6AC7}{\mathfrak{N}}-1)^{2^5}-1\right)\right)+4 = log 2 ( log 2 ( 2 2 5 ) ) + 4 \Large =\log_2\left(\log_2\left(2^{2^5}\right)\right)+4 = 5 + 4 = 9 \huge =5+4=\boxed 9

C RAZY F ANCY L ATEX ( + 1 ) \begin{matrix} \color{#20A900}{\mathscr{C}\text{RAZY}} \\ \color{#D61F06}{\mathscr{F}\text{ANCY}} \\ \color{#3D99F6}{\mathscr{L}\text{ATEX}} \\ \color{#EC7300}{(+1)}\end{matrix} I loved solving this problem ¨ \ddot \smile !I was eager to write a solution for it as well.You beat me :(

Rohit Udaiwal - 5 years, 1 month ago

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T H A N K S ! \huge\mathbf{\color{#D61F06}{T}\color{#3D99F6}{H}\color{#EC7300}{A}\color{#20A900}{N}\color{#69047E}{K}\color{#E81990}{S}}\color{#624F41}{!}

Haha... I also think the same after solving your questions.. But like you I also make sure that I'm the first to post a solution to my question... :-)

Rishabh Jain - 5 years, 1 month ago

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It's obviously a problem poser's 'right' to show off his mathematical creativity :)

Rohit Udaiwal - 5 years, 1 month ago

The answer is easily guessable.(do you see why? :P :P)

Nihar Mahajan - 5 years, 1 month ago

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@Nihar Mahajan Obviously not :P otherwise I would have modified it... :\ but I tried my best to make the problem guess proof.. Maybe I would have made it decimal type..

Rishabh Jain - 5 years, 1 month ago

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@Rishabh Jain Intuitively, you can see the expression as log 2 ( log 2 ( ( s o m e t h i n g ) 2 5 ) ) ) = 5 \log_2(\log_2((something)^{2^5}) ))=5 and the rest follows XD

Nihar Mahajan - 5 years, 1 month ago

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@Nihar Mahajan Really?? :-) ... Did you applied the same theorem to solve the question?? :-D

Rishabh Jain - 5 years, 1 month ago

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@Rishabh Jain Yes. I call it "Axiom of Guessology" LOL!

Nihar Mahajan - 5 years, 1 month ago

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@Nihar Mahajan Yeah and you deserve a g u e s s o s c a r guess\color{#D61F06}{oscar} for that.... But I don't know who will present it to you.. Lol :/

Rishabh Jain - 5 years, 1 month ago

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@Rishabh Jain Ok, here's a fun problem . :P

Nihar Mahajan - 5 years, 1 month ago

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@Nihar Mahajan Already done... Habort has already posted a solution... Lol ...you should greet him ..

Rishabh Jain - 5 years, 1 month ago

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@Rishabh Jain I only told him to post a solution Or I would have posted it :P

Nihar Mahajan - 5 years, 1 month ago

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