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17 votes
2 answers
1k views

Crazy integral with nested radicals and inverse sines

Recently a friend who is writing a book on integrals added this problem to his book: $$\int_{0}^{1}\arcsin{\sqrt{1-\sqrt{x}}}\ dx=\frac{3\pi}{16}$$ After a while, when trying to generalize, I was able ...
pvr95's user avatar
  • 529
3 votes
0 answers
64 views

Does this ridiculous integral converge?

I was looking through some of my older questions, when I came across this crazy integral I posted. $\int\limits^{2}_{1}\sqrt{x-\sqrt{x!-\sqrt{(x!)!-\sqrt{((x!)!)!-\dots}}}}dx$ I had approximated it at ...
Dylan Levine's user avatar
  • 1,686
1 vote
0 answers
130 views

A very interesting integral: $\int\limits^{2}_{1}\sqrt{x-\sqrt{x!-\sqrt{(x!)!-\sqrt{((x!)!)!-\dots}}}}dx$

I really like infinitely nested radicals so when I was messing around with them in Desmos, I noticed that the domain of $\sqrt{x-\sqrt{x!-\sqrt{(x!)!-\sqrt{((x!)!)!-\dots}}}}$ seemed to converge to $1&...
Dylan Levine's user avatar
  • 1,686
10 votes
1 answer
274 views

Evaluate: $\int_0^1 \sqrt{x+\sqrt{x^2+\sqrt{x^3+\cdots}}}\, dx. $

Is there a way to evaluate the integral:$$\int_0^1\sqrt{x+\sqrt{x^2+\sqrt{x^3+\sqrt{x^4+\cdots}}}}\,dx,$$ without using numerical methods? The integrand doesn't seem to converge to anything for any ...
Dhrubajyoti Bhattacharjee's user avatar
0 votes
0 answers
114 views

How to evaluate the integral $\int_{-1}^{0}\sqrt{1+\sqrt{1+\sqrt{1+\sqrt{\cdots\sqrt{1+x}}}}}dx=?$

We have : $$\int_{-1}^{0}\sqrt{1+\sqrt{1+\sqrt{1+x}}}dx=\frac{8}{315}\sqrt{2}\Big(16+\sqrt{233+317\sqrt{2}}\Big)$$ We are lucky because this integral have an anti-derivative like here. More ...
Ranger-of-trente-deux-glands's user avatar
14 votes
1 answer
414 views

Unsure of my work evaluating $\int \frac{dx}{\sqrt{x + \sqrt{x + \sqrt{x + \cdots}}}}$

This Question is an Extension of this Previously Asked Question: Nested root integral $\int_0^1 \frac{dx}{\sqrt{x+\sqrt{x+\sqrt{x}}}}$ I was looking into answering the question of whether it was ...
Eric L's user avatar
  • 1,957
12 votes
1 answer
386 views

How would you prove $\int^8_0\frac1{\sqrt{x+\frac1{\sqrt{x}}}}dx<4-\frac1{2019}$?

We would like to prove the following inequality. $$\int^{8}_{0}\frac{1}{\sqrt{x+\frac{1}{\sqrt{x}}}}\,dx<4-\frac{1}{2019}\tag{1}$$ What I've tried is using the AM-GM inequality, $$x+\frac{1}{\...
maths-maths's user avatar
0 votes
1 answer
99 views

An approximation for an integral involving nested radicals and logarithms

Yesterday I wrote some simple integrals involving nested radicals, and/or continued fractions. This was an example with nested radicals, let $$\int_0^1\frac{dx}{\sqrt{1+(\log x)g(x)}},\tag{1}$$ where $...
user avatar
8 votes
2 answers
1k views

Solve $ \int_0^2 \sqrt{x+\sqrt{x+\sqrt{x+\dotsb}}}\,dx $

I haven't seen this question, but if someone has, it would be very appreciated if you could send a link! I've been very interested in the MIT Integration Bee, and one question that stood out to me ...
Tom Himler's user avatar
  • 2,304
2 votes
1 answer
133 views

On the integral $\int_0^1 \frac{dx}{\sqrt[3]{x+\sqrt[3]{x+\sqrt[3]{x+\cdots}}}}$ and the plastic constant

We have, $$\phi=\sqrt{1+\sqrt{1+\sqrt{1+\cdots}}}$$ $$P=\sqrt[3]{1+\sqrt[3]{1+\sqrt[3]{1+\cdots}}}$$ with golden ratio $\phi$ and plastic constant $P$. If, $$\int_0^1 \frac{dx}{\sqrt{x+\sqrt{x+\...
Tito Piezas III's user avatar
26 votes
2 answers
1k views

How to find $\lim_{n \to \infty} \int_0^1 \cdots \int_0^1 \sqrt{x_1+\sqrt{x_2+\sqrt{\dots+\sqrt{x_n}}}}dx_1 dx_2\dots dx_n$

Here I mean the limit of the following sequence: $$p_1=\int_0^1 \sqrt{x} ~dx=\frac{2}{3}$$ $$p_2=\int_0^1 \int_0^1 \sqrt{x+\sqrt{y}} ~dxdy=\frac{8}{35}(4 \sqrt{2}-1) = 1.06442\dots$$ $$p_3=\int_0^...
Yuriy S's user avatar
  • 31.6k
36 votes
1 answer
3k views

Nested root integral $\int_0^1 \frac{dx}{\sqrt{x+\sqrt{x+\sqrt{x}}}}$

The bigger goal is to find the antiderivative: $$\int \frac{dx}{\sqrt{x+\sqrt{x+\sqrt{x}}}}~~~~~(*)$$ But I can settle for the definite integral in $(0,1)$. Motivation: $$\int \frac{dx}{\sqrt{x+\...
Yuriy S's user avatar
  • 31.6k
15 votes
1 answer
417 views

An incorrect answer for an integral

As the authors pointed out in this paper (p. 2), the following evaluation which was in Gradshteyn and Ryzhik (sixth edition) is incorrect (and has been removed). $$ ''\int_{0}^{\infty}\frac{1}{\left(1+...
Olivier Oloa's user avatar