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154 votes
15 answers
55k views

Are there real-life relations which are symmetric and reflexive but not transitive?

16 votes
4 answers
2k views

Donald Knuth's summation notation confuses me.

14 votes
4 answers
686 views

Is there a closed form for the series $\sum_{k=1}^\infty \frac{\ln(4k-3)}{(4k-3)}-\frac{\ln(4k-1)}{(4k-1)}?$

12 votes
1 answer
1k views

What is $f(x)$ divided by $(x-a)$?

10 votes
5 answers
1k views

What is the coefficient of the $x^3$ term in the expansion of $(x^2+x-5)^7$ (See details)?

8 votes
3 answers
7k views

Proving that $S_n$ has order $n!$

8 votes
2 answers
4k views

Is there a unique solution for this quadratic matrix equation?

8 votes
3 answers
203 views

How do I read this question? (subject: bijections)

6 votes
2 answers
2k views

Proving a commutative ring can be embedded in any quotient ring.

6 votes
1 answer
2k views

Is this a correct proof that all rational functions are integrable?

5 votes
1 answer
219 views

Implicit Differentiation of $x^2y+y^5\sec(x)=5$.

4 votes
3 answers
4k views

Probability of 15 consecutive green lights

4 votes
1 answer
3k views

Solution Sets of Trigonometric Equations

4 votes
3 answers
1k views

What is the limit of a sequence defined recursively as $x_1=2$, $x_{n+1}=\frac{1}{3-x_n}$ with $n \in \mathbb{N}$, and how do I prove it exists?

3 votes
1 answer
634 views

Why does $\frac{s}{s-1} > \zeta(s) > \frac{1}{s-1}$ imply $\lim_{s \to 1^{+}}(s-1)\zeta(s)=1$?

2 votes
1 answer
79 views

$n^s=(n)_s+f(s)$, what is $f(s)$?

2 votes
1 answer
71 views

What is a more natural example of the following?

2 votes
2 answers
239 views

Is $\left|\left[\frac{1}{7,000,000,000},1\right]\right|<\left|[0,1]\right|$?

1 vote
1 answer
132 views

How can one differentiate with respect to variable upperbounds in summations?

0 votes
1 answer
72 views

Laplace transform identity: $\mathcal{L}[f^{(n)}(t)/t^m](s)=?$

0 votes
1 answer
153 views

Does every equivalence relation on set $S$ containing binary relation $C$ contain equivalence relation $E$?