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23h
comment Is is possible that three countries have three points in common?
@wythagoras: But the Lakes of Wada each consist of one piece, don't they?
2d
comment Summation of a term to infinity
@Kevin: What do you mean, "not the traditional epsilon-delta definition"? Why not?
2d
comment Each alphabet of KANGAROO is replaced with number by $2$ people; which alphabet is replaced with the same number?
That's not quite right: the sum of the even and odd digits differs by a multiple of $11$. So you could have, for instance, $K=9, N=5, G=1, R=2$.
2d
revised Integral from $-\infty$ to $\infty$ of a function?
deleted 1 character in body
2d
comment Integral from $-\infty$ to $\infty$ of a function?
This implies that every odd function is integrable, which is certainly not true.
2d
comment Solve equation $\frac{1}{x}+\frac{1}{y}=\frac{2}{101}$ in naturals
It's clear enough. Just express it as a single fraction, and you get a solution different from the obvious $x=y=101$.
Feb
11
comment How to form a recurrence for a $n$-digit sequence using digits $0,1,2,3$ so that we have even no of $0$'s?
I like this!${}$
Feb
11
comment prove that the quadrilateral $ABCD$ is a square
I've never seen wronger right angles!
Feb
11
comment prove that the quadrilateral $ABCD$ is a square
It's not even almost true.
Feb
11
comment Proving that $6|n(n + 1)(n + 2)$ for any integer $n \geq 1$
What does the title have to do with the question?
Feb
10
revised Solving $e^{\sin(z)}=1$ in the complex plane
edited title
Feb
10
revised Decimals of the square root of $n$.
edited body
Feb
10
answered Decimals of the square root of $n$.
Feb
9
comment Sums of remainders in Euclidean GCD algorithm
@ThomasAndrews: $\log_2 3$ looks strange in this context! I will have to do some research of my own.
Feb
9
comment Sums of remainders in Euclidean GCD algorithm
@wvxvw: I wouldn't recommend that approach. The problem is, it has a terrible worst-case behaviour (specifically, if one of the arguments is much smaller than the other).
Feb
8
comment Sums of remainders in Euclidean GCD algorithm
It's a bit late over here, so I'm not up to doing the sums right now. But I have a feeling that your "roughly 1/2" will turn out to be $1/\varphi$ in the limit.
Feb
8
comment Why is this derivative not undefined at a given point?
"if 0 is neither a maximum nor a minimum on on g(x) at x=c, then we can conclude that there exists an interval...": This is actually wrong. $g(x)=x^2\sin\dfrac{1}{x}$ at $c=0$ is a counterexample.
Feb
8
revised Can $f''(x)$ exist if $f'(x)$ is undefined?
edited title
Feb
8
comment Let $f:\mathbb{R}\rightarrow\mathbb{R}$ be a function such that $f'(x)$ is continuous and $|f'(x)|\le|f(x)|$ for all $x\in\mathbb{R}$
If $f$ satisfies the given conditions, then so does $\alpha f$ for any $\alpha \in \mathbb R$. Hence, if $f(5)$ has a maximum possible value, that value must be $0$.
Feb
8
comment Understanding the definition of the sign of a permutation , $\operatorname{sgn}(\pi) = (-1)^k$ .
Very nice.${}{}$