Skip to main content
Mathematics

Top Questions

Ask Question
Interesting 9 Bountied Hot Week Month
12 votes
5 answers
439 views

Non-recursive, explicit rational sequence that converges to $\sqrt{2}$

Mikhail Katz's user avatar
Mikhail Katz
  • 49.1k
10 votes
4 answers
1k views

Why Is the Dual Basis Mathematically Unavoidable?

Nicolas Malebranche's user avatar
Nicolas Malebranche
  • 111
13 votes
2 answers
1k views

Is this formula for cosine correct? (And is it significant) [closed]

Bruno Andrades's user avatar
Bruno Andrades
  • 5,288
13 votes
2 answers
1k views

Is the transfer principle useless?

Henry's user avatar
Henry
  • 741
7 votes
5 answers
279 views

Are there any other special mathematical definitions like $0! =1$ to ensure consistent and valid results?

T﹏T's user avatar
T﹏T
  • 3,240
7 votes
2 answers
1k views

Why does this method work some of the time (but only some?)

true blue anil's user avatar
true blue anil
  • 49.6k
10 votes
4 answers
285 views

Evaluate: $4^9-\binom{8}{1}4^8+\binom{7}{2}4^7-\binom{6}{3}4^6+\binom{5}{4}4^5$

D S's user avatar
D S
  • 5,842
7 votes
4 answers
309 views

What is the correct definition of a limit point in real analysis?

user21820's user avatar
user21820
  • 61.3k
11 votes
1 answer
717 views

Why do these valleys in $LCM(P_n - 1, P_n + 1) \bmod n$ exist and are they random?

philipxy's user avatar
philipxy
  • 129
11 votes
1 answer
472 views

Does every (possibly infinite dimensional) vector space have an orthogonal Hamel basis?

Bruno Andrades's user avatar
Bruno Andrades
  • 5,288
6 votes
4 answers
333 views

Is there a closed form for integral $\int_0^\infty \frac{\ln(1+x^2)}{x^2+2a x+1}dx $ with $|a|<1$

Claude Leibovici's user avatar
Claude Leibovici
  • 297k
9 votes
1 answer
477 views

Do division rings have algebraic closures?

KCd's user avatar
KCd
  • 57k
3 votes
2 answers
387 views

Coloring a graph with K-colors

Bruno Andrades's user avatar
Bruno Andrades
  • 5,288
5 votes
2 answers
230 views

On $\int_0^{\frac{\pi}{2}}x\sin\left({\small\frac12}\tan{x}\right)dx=\frac{\pi}{4}\,\frac{\gamma+\delta}{\sqrt{e}}$

Maxime Jaccon's user avatar
Maxime Jaccon
  • 5,205
7 votes
3 answers
278 views

Telescopic series: how to identify it after breaking it down into partial fractions?

RobPratt's user avatar
RobPratt
  • 52.3k
4 votes
1 answer
263 views

Examples of countable non-commutative division rings

Noah Schweber's user avatar
Noah Schweber
  • 264k
6 votes
2 answers
195 views

When does $a^n+1$ have $n$ divisors?

Dietrich Burde's user avatar
Dietrich Burde
  • 143k
4 votes
2 answers
373 views

"Probable" Sets

Markus Klyver's user avatar
Markus Klyver
  • 2,543
8 votes
2 answers
266 views

Show that if $\frac{f'}{g'}$ increases, then $\frac{f}{g}$ is increasing

Paramanand Singh's user avatar
Paramanand Singh♦
  • 92.9k
4 votes
5 answers
199 views

Why is the expansion of numbers in other bases always in base $10$?

Dan's user avatar
Dan
  • 19.2k
3 votes
2 answers
403 views

The intuition behind defining trigonometric functions in the complex plane as special combinations of exponential functions [closed]

user494137's user avatar
user494137
  • 41
5 votes
3 answers
497 views

Does truth not exist in ZFC, or is it merely not definable?

Mikhail Katz's user avatar
Mikhail Katz
  • 49.1k
3 votes
3 answers
327 views

How many ways to arrange BOOKKEEPER where two E’s appear consecutively but not three.

true blue anil's user avatar
true blue anil
  • 49.6k
5 votes
3 answers
234 views

Expectation of an absolute value

Letac Gérard's user avatar
Letac Gérard
  • 3,985
1 vote
2 answers
107 views

Find the number of quadruples of non negative integers $(a,b,c,d)$ such that $105a + 70b + 42c + 30d = 2025$

Cuckoo Beats's user avatar
Cuckoo Beats
  • 575
3 votes
2 answers
134 views

In the Pell's equation $a^2-2b^2=1$, is $a$ always of the form $k^2\pm 1$?

J. W. Tanner's user avatar
J. W. Tanner
  • 64.5k
3 votes
2 answers
268 views

Recursively enumerable sets and the natural numbers

Noah Schweber's user avatar
Noah Schweber
  • 264k
5 votes
2 answers
178 views

Evaluating triple integral $\int_0^1 \int_0^1 \int_0^1 \frac{x + y^2 + z^3}{\sqrt{x + y + z}}\,dx\,dy\,dz$

whpowell96's user avatar
whpowell96
  • 7,754
1 vote
6 answers
164 views

Calculating $i^{3/2}$ in two ways gives different results [closed]

Dan's user avatar
Dan
  • 19.2k
5 votes
1 answer
260 views

Where to find Nardin's lecture notes on stable homotopy theory?

Scientifica's user avatar
Scientifica
  • 9,078
4 votes
1 answer
184 views

Sum of two independent chi-squared random variables

D.W.'s user avatar
D.W.
  • 6,030
4 votes
2 answers
183 views

Cutting a Möbius strip in thirds. Why are the resulting strips interlinked?

heropup's user avatar
heropup
  • 146k
4 votes
1 answer
275 views

Can an absolutely convergent infinite linear combination of an algebraically independent family be algebraic?

KELVIN LAM's user avatar
KELVIN LAM
  • 43
0 votes
1 answer
115 views

Is the matrix A invertible? [closed]

Daniele Tampieri's user avatar
Daniele Tampieri
  • 11k
2 votes
4 answers
187 views

Finding the angles of a non-equilateral $\triangle ABC$ with centroid $G$ such that $\angle GAB=\angle GCA=30^\circ$

Blue's user avatar
Blue
  • 85.2k
2 votes
2 answers
232 views

Does the Axiom Schema of Separation in any sense "provide" only countably many definitions of subsets of $\mathbb{N}$?

Chad K's user avatar
Chad K
  • 5,547
3 votes
2 answers
218 views

Showing the Cayley transform sends positive definite matrices to small matrices and vice versa

Moh's user avatar
Moh
  • 491
0 votes
3 answers
127 views

Show that if $(z_1+\frac{a}{z_1})(z_2+\frac{b}{z_2}) \in \mathbb R^*$, then there exists $k \in \mathbb R^*$ such that $z_2=k\cdot \overline{z_1}$. [closed]

user's user avatar
user
  • 28.1k
6 votes
2 answers
93 views

Intuition behind using $\pi$-system in Measure Theory

Michael Greinecker's user avatar
Michael Greinecker
  • 35.4k
5 votes
1 answer
176 views

Quotient group technicality

Derek Holt's user avatar
Derek Holt
  • 98.3k
-3 votes
4 answers
210 views

Find $ \lim_{x\to+\infty} \left( \frac{x^{2}+3}{3x^{2}+1} \right)^{x^{2}}=0 $ [closed]

Ryszard Szwarc's user avatar
Ryszard Szwarc
  • 46.9k
8 votes
1 answer
201 views

Asymptotics of $\sum_{n=0}^\infty (-1)^n x^{2^n}$ near $x = 1$

K B Dave's user avatar
K B Dave
  • 10.1k
2 votes
3 answers
199 views

Prove $AF, BC, GE$ are concurrent in a tangent–circumcircle configuration

D S's user avatar
D S
  • 5,842
3 votes
3 answers
153 views

Prove that $\sqrt{x+y+z}\;\ge\;\sqrt{x-1}+\sqrt{y-1}+\sqrt{z-1}$

Raymond Martin's user avatar
Raymond Martin
  • 1
4 votes
2 answers
92 views

Construction of a dense linear order with $2^\kappa$ cuts

Holo's user avatar
Holo
  • 10.5k
3 votes
1 answer
189 views

Comparison of Dedekind-finite sets

Noah Schweber's user avatar
Noah Schweber
  • 264k
4 votes
1 answer
186 views

Is there a converse of the Copeland-Erdős theorem on normal numbers?

Jotazuma's user avatar
Jotazuma
  • 162
3 votes
1 answer
300 views

What are the moments of the average operator?

Henry's user avatar
Henry
  • 172k

Looking for more? Browse the complete list of questions, or popular tags. Help us answer unanswered questions.