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Martin Cohen is a retired computer programmer who loves dancing (favorites are West Coast Swing, Waltz, Foxtrot, and Salsa), writing (but not revising) poems, and solving math problems (that's why I'm here). He is currently trying to learn improv at the Westside Comedy Theater (westsidecomedy.com) in Santa Monica, CA.

He can also be reached at mjcohen@acm.org.


11h
comment How many ways can one “fit” $m$ non-overlapping sub-segments of length $k$ into a segment of length $n$?
Don't have time to do more than wave my hands wildly, but possibly induction on n starting at n = m*k. Also, are the m sub-segments distinguishable or not?
11h
comment Showing that $\lim_{x\to\infty}\left(\sqrt{x^2+c}-x\right)=0$
But only for $x=0$. Anyway, the OP's question has $x \to \infty$.
15h
comment Showing that $\lim_{x\to\infty}\left(\sqrt{x^2+c}-x\right)=0$
I don't see whay a separate discussion when $c=0$ is necessary. This looks true whenever $x^2 \ge |c|$.
15h
comment Why is $(1-\cot 37^\circ)(1-\cot 8^\circ)=2.00000000\cdots$?
Because of David H's answer
15h
revised Limit of $\sqrt[n]{(x+1)…(x+n)} - x$ as $x \to +\infty$
added additional result and explanation
2d
comment Proving an identity involving the product of the Möbius function and Euler’s totient function.
Sorry. I have been dinged here for helping too much, and you should certainly be able to do this with the hints I have provided.
2d
answered Limit of $\sqrt[n]{(x+1)…(x+n)} - x$ as $x \to +\infty$
2d
comment Proving an identity involving the product of the Möbius function and Euler’s totient function.
The sum over divisors of a multiplicative function is also multiplicative, so you only have to look at the sum for powers of primes. What is special when the prime is 2?
2d
answered If $\lim_{x\rightarrow \infty}\left[\left(x^5+7x^4+2\right)^c-x\right]$ is a finite, Then limit is
2d
comment Proving an identity involving the product of the Möbius function and Euler’s totient function.
Hint: $\mu$ and $\phi$ are both multiplicative functions, so their product also is. What do you know about multiplicative functions and summing them over divisors?
2d
answered Subjects or recent progress in Tropical geometry or similar suitable for undergraduate investigation
2d
comment Sign of Ramanujan $\tau$ function
Perhaps a "useful" closed form formula was meant. Oy.
2d
comment $\frac {1}{5}-\frac{1.4}{5.10}+\frac{1.4.7}{5.10.15}-\cdot\cdot\cdot\cdot\cdot\cdot\cdot$
This question is not missing context, and is perfectly clear, at least to me. How do I vote to keep it open?
2d
comment Want to find the maximum of an unnormalised density function.
What does my approximation give? I don't know your values for $b$ and $W$.
Nov
24
answered How prove this $n$ smaller cubes ( length is $1,2,3,\cdots,n$) can't Mosaic a big cube
Nov
24
revised $\frac {1}{5}-\frac{1.4}{5.10}+\frac{1.4.7}{5.10.15}-\cdot\cdot\cdot\cdot\cdot\cdot\cdot$
added generalizations
Nov
24
answered $\frac {1}{5}-\frac{1.4}{5.10}+\frac{1.4.7}{5.10.15}-\cdot\cdot\cdot\cdot\cdot\cdot\cdot$
Nov
24
comment Find the limit $\lim_{x\to 0^-}| \left( 1+x^{3} \right)^{1/2}-1-x^{5} |/(\sin x-x)$
Fixed it. Thanks.
Nov
24
revised Find the limit $\lim_{x\to 0^-}| \left( 1+x^{3} \right)^{1/2}-1-x^{5} |/(\sin x-x)$
Fixed error
Nov
24
answered Find the limit $\lim_{x\to 0^-}| \left( 1+x^{3} \right)^{1/2}-1-x^{5} |/(\sin x-x)$