Mathematics Stack Exchange

3

votes

1

answer

31

views

How to construct the matrix of a 2-D system of differential equations

ordinary-differential-equations systems-of-equations approximation-theory linear-approximation

answered 2 mins ago E.Nole 802

0

votes

2

answers

12

views

Find points where the plane $6x+y+9z=54$ intersects each coordinate axis.

calculus vector-spaces

answered 3 mins ago user170231 7,202

0

votes

1

answer

12

views

How do I finish deriving this property of normal subgroups?

abstract-algebra group-theory normal-subgroups

answered 3 mins ago devianceee 1,045

1

vote

1

answer

7

views

Finding area of a triangle from incircle of a square and given intersection lines.

geometry triangles

answered 4 mins ago Alexey Burdin 2,015

1

vote

1

answer

8

views

How long will it take to catch up to a stream?

calculus

answered 4 mins ago Saket Gurjar 1,384

0

votes

0

answers

4

views

range of variation for a conditional entropy

entropy

asked 4 mins ago Sultan Akhmetbek 1

0

votes

1

answer

11

views

Derive the power series expansion for he local stable and unstable manifolds of the ODE $x'=(-x_1+x_2^2,2x_2+x_1x_2)$ for the singularity $(0,0)$

ordinary-differential-equations dynamical-systems

answered 4 mins ago John B 13.8k

1

vote

0

answers

45

views

A question about functional analysis.

functional-analysis

modified 5 mins ago user780498 29

1

vote

0

answers

19

views

Let $f \colon X \rightarrow X$ continuous. Show that if $X = [0,1]$, then there exists a point $x$ such that $f(x) = x$

general-topology

modified 5 mins ago Jhöśë Elijäh 171

0

votes

1

answer

8

views

Volume of truncated pyramid triangle base

geometry

modified 5 mins ago Harish Chandra Rajpoot 32k

0

votes

2

answers

10

views

Determine the limit of $a_n$ where $\{a_n\} $ $n\ge1$ be a sequence of real numbers defined by $a_{n+1}= \frac{3a_n}{2+a_n}$.

sequences-and-series

modified 6 mins ago The73SuperBug 263

0

votes

0

answers

8

views

invertible matrices and demensions

matrices

asked 7 mins ago Lampert12 1

0

votes

0

answers

5

views

Geometry equations

geometry

asked 8 mins ago tibi 1

0

votes

0

answers

3

views

Let the set S = { \begin{bmatrix}a&b\\2b&c\end{bmatrix} } | ∀ a,b,c ∈ ℝ}

linear-algebra

asked 8 mins ago Sam23132 1

0

votes

0

answers

2

views

Pullback of intersection of two subobjects

category-theory sheaf-theory topos-theory

asked 11 mins ago Pouya Layeghi 181

0

votes

0

answers

11

views

Find the area inside the outer loop and the outside the inner loop of the limacon $r=6\cos(\theta)-3$

calculus parametric

modified 11 mins ago adnyu.js 1

0

votes

0

answers

12

views

Least-squares matrix exponential

least-squares

modified 12 mins ago Electer 1

0

votes

0

answers

4

views

Calculate coordinates of polygon's points after changing lenght of one side

vector-spaces coordinate-systems polygons

asked 13 mins ago MineFuf LP 1

0

votes

0

answers

23

views

Use the Laurent series to prove that $\int_{0}^{2 \pi} e^{\cos(t)} \cos(nt-\sin t)\,dt=\frac{2 \pi}{n!}$

integration complex-analysis laurent-series

modified 14 mins ago Samuel Martinez 135

0

votes

0

answers

11

views

Integrate $\int_0^{2\pi} \frac{(\cos^2{x})^{2-\beta}}{(1+\alpha \cos{x})^{4-\beta}} dx$

integration complex-analysis indefinite-integrals contour-integration residue-calculus

modified 15 mins ago Warrenmovic 121

2

votes

1

answer

22

views

Number of routes not passing in 3 points

combinatorics

modified 15 mins ago David G. Stork 20.1k

0

votes

0

answers

5

views

To what extent does Goedel's 2nd incompleteness theorem extend?

first-order-logic incompleteness

asked 16 mins ago dre rt 13

3

votes

1

answer

33

views

What is intuition behind matrix differentiation?

calculus matrix-calculus

answered 21 mins ago Derek O 163

2

votes

0

answers

7

views

A variation in the construction of the tensor product of modules

abstract-algebra modules tensor-products

asked 23 mins ago alf262 47

0

votes

1

answer

15

views

Can a unit of currency be taken to n power?

exponentiation finance unit-of-measure

modified 23 mins ago DominicTarro 36

0

votes

0

answers

12

views

Polynomial such that $a\mid p(a)$, for all $a\in\mathbb{R}$, $a\neq 0$. (Problem with divisibility in $\mathbb{R}$.)

polynomials

modified 25 mins ago Bernard 148k

2

votes

1

answer

27

views

Where is the mistake with this conditional expectation calculation?

probability conditional-expectation expected-value

answered 27 mins ago heropup 77.9k

-1

votes

0

answers

17

views

Is there $u: \mathbb{R} \times [0,T] \rightarrow \mathbb{R}$ such that $u_t = u_{xx}, u(x,0) = 0$?

partial-differential-equations heat-equation

asked 27 mins ago Naah 319

0

votes

0

answers

12

views

Number of ordered triples, given upper bounds?

probability combinatorics

modified 27 mins ago MonsieurGalois 4,838

4

votes

1

answer

56

views

Is it true that $\mathbb{E}\left[\sum\limits_{k=1}^m \frac{\frac{1}{X_k}}{\sum_{j=1}^m \frac{1}{X_j}}\chi_{(r,+\infty)}(X_k)\right]\to0,m\to\infty?$

probability-theory convergence-divergence rate-of-convergence

modified 28 mins ago Bob 3,366

1

vote

0

answers

8

views

Question about the definition of the arc length of the graph of a function

real-analysis arc-length

asked 28 mins ago Zacharias Zarowski 150

0

votes

1

answer

9

views

Cantor Ternary Set Problem, Ternary Expansions

measure-theory lebesgue-measure cantor-set

modified 28 mins ago Brian M. Scott 495k

0

votes

0

answers

2

views

Additivization of functors in an abelian monoidal category

category-theory abelian-categories monoidal-categories functors

asked 28 mins ago Isaac Ren 1,289

0

votes

0

answers

17

views

Stewart theorem validity on a sphere

spherical-trigonometry

modified 32 mins ago Narasimham 26.7k

0

votes

0

answers

19

views

Unclear theorem about unitary transformations

linear-algebra quantum-computation unitary-matrices

modified 32 mins ago catalyst 1

0

votes

0

answers

5

views

Conclusion of implicit function theorem in local lie group

complex-analysis lie-groups lie-algebras implicit-function-theorem complex-manifolds

modified 33 mins ago Ibs 162

0

votes

0

answers

3

views

Can a Hamiltonian cycle of an undirected Cayley graph contain inverses of the generating elements?

graph-theory finite-groups hamiltonian-path cayley-graphs hamiltonicity

asked 34 mins ago Buddhini Angelika 611

0

votes

1

answer

17

views

Two different formulas for determining the angle in polar coordinate system

polar-coordinates

modified 34 mins ago number 109

0

votes

0

answers

23

views

Is there a difference between rolling 3d6 and rerolling lowest twice, versus rolling 5d6 and dropping the two lowest values?

statistics dice

modified 35 mins ago Leucippus 21.9k

0

votes

0

answers

29

views

Modification of inequalities with real numbers.

real-numbers

modified 36 mins ago Mikhail Botchkarev 1

-1

votes

0

answers

19

views

Finding minimum value when roots are irrational.

quadratics

modified 36 mins ago miracle173 8,243

0

votes

1

answer

9

views

Help finding integer squares in parametric quadratic equation

quadratics parametric

answered 38 mins ago Alexey Burdin 2,015

1

vote

0

answers

9

views

Gradient of a cross product of a vector and second rank tensor

vector-analysis tensors cross-product

asked 41 mins ago Archisman Panigrahi 1,290

0

votes

0

answers

7

views

How do I find the equation of a logarithmic spiral (in polar form) passing through a certain amount of points?

logarithms polar-coordinates regression

asked 41 mins ago Ahmed 1

0

votes

1

answer

91

views

+50

Prove that, for each $n\in\mathbb{N}$, $f_n(z)=|z|e^{in\arg(z)}$ is Lipschitz with constant n.

complex-analysis functional-analysis lipschitz-functions

modified 42 mins ago Oliver Diaz 3,114

0

votes

0

answers

13

views

Is my attempt at constructing this homomorphism correct?

abstract-algebra

asked 43 mins ago Patrick Browne 151

0

votes

2

answers

16

views

For PCA using the eigenvectors of the covariance matrix, what is the meaning of the eigenvalues?

linear-algebra

modified 46 mins ago parsiad 21.3k

1

vote

0

answers

18

views

Dirichlet Test For Convergence Of Improper Integrals

calculus

modified 46 mins ago Michael Hardy 235k

1

vote

0

answers

12

views

Finding real affine change of coordinates efficiently

algebraic-geometry

asked 48 mins ago Tarang Saluja 189

1

vote

1

answer

23

views

Is it true that $u$ is harmonic if and only if $u$ satisfies the mean value property?

integration multivariable-calculus partial-differential-equations harmonic-functions

answered 51 mins ago Ivo Terek 58.4k

2

votes

1

answer

13

views

Why distance function differentiable for sufficiently smooth boundary?

real-analysis derivatives differential-geometry partial-differential-equations elliptic-equations

answered 56 mins ago Angina Seng 133k

0

votes

0

answers

14

views

how do i find the equation of major and minor axis?

linear-algebra algebra-precalculus conic-sections

modified 1 hour ago user376343 5,015

0

votes

0

answers

18

views

Counting: How many ways to choose 5 items from 3 groups, where items in a group are indistinguishable?

probability combinatorics

modified 1 hour ago James Flanagin 49

0

votes

0

answers

8

views

Properties of a mapping

polynomials diophantine-equations

asked 1 hour ago thestar 33

1

vote

0

answers

20

views

Complex Ordinary Differential Equations

complex-analysis ordinary-differential-equations complex-integration

modified 1 hour ago Mr. N 425

-1

votes

1

answer

30

views

Infinite primes in Arithmetic progression

number-theory elementary-number-theory prime-numbers algebraic-number-theory analytic-number-theory

answered 1 hour ago A.G 1,029

0

votes

2

answers

43

views

Evaluating the integral $\int^{\infty}_{-\infty} \frac{dx}{x^4-2\cos(2\theta)x^2 +1}$

integration complex-analysis contour-integration complex-integration branch-cuts

answered 1 hour ago Integrand 2,602

0

votes

0

answers

16

views

Erreur MAPLE [I did not understand how to solve this problem]

maple

asked 1 hour ago Abdellah El Iraoui 1

0

votes

0

answers

6

views

Getting a Bivariate Polynomial From a Zero-Set

geometry polynomials

asked 1 hour ago wjm 5,639

1

vote

0

answers

14

views

Limit, supremum and sets

real-analysis limits continuity solution-verification

asked 1 hour ago RLC 1,182

0

votes

0

answers

23

views

Measure of union of diagonals

measure-theory

modified 1 hour ago dragoboy 1,448

1

vote

1

answer

12

views

Preimage of multivariable function is convex

analysis multivariable-calculus convex-analysis

answered 1 hour ago copper.hat 144k

0

votes

0

answers

19

views

What is the Gaussian Integral for negative $n$ exponents?

gaussian-integral

modified 1 hour ago user170231 7,202

1

vote

0

answers

10

views

Finding the number of (real) solutions of polynomials and their location on the x-axis

polynomials arithmetic roots intuition

asked 1 hour ago PrincepsMaximus 11

0

votes

0

answers

17

views

About the vector space $L(D)$ associated to a divisor

algebraic-geometry algebraic-curves

modified 1 hour ago Bernard 148k

1

vote

1

answer

11

views

Unusual skein relation in HOMFLY polynomial

knot-theory knot-invariants

answered 1 hour ago Kyle Miller 12.6k

0

votes

0

answers

7

views

Is it necessarily that outdegree of every vertex in digraph G(order$\geq 2$) equals 1?

graph-theory

modified 1 hour ago Damascuz 56

0

votes

1

answer

13

views

term for distance preserving up to scale

metric-spaces riemannian-geometry conformal-geometry

modified 1 hour ago AndyP 381

1

vote

0

answers

10

views

Prove that orthocenter of the triangle formed by the arc midpoints of triangle ABC is the incenter of ABC

geometry euclidean-geometry triangles circles

asked 1 hour ago Josh Goldman 95

1

vote

0

answers

27

views

A Curve Over Finite Field

abstract-algebra finite-fields irreducible-polynomials curves

modified 1 hour ago nomadd 57

0

votes

0

answers

16

views

Additional Clarification on a Question on Lebesgue Outer Measure?

lebesgue-integral lebesgue-measure

modified 1 hour ago Arbuja 66

0

votes

0

answers

4

views

Continuous variable function that evaluates to random curves

random-variables random random-functions

asked 1 hour ago Andreu Heisenberg 25

2

votes

1

answer

23

views

Clarification about Quotient Ring Isomorphism Theorem for a Principal Ideal

ring-theory ideals ring-isomorphism

answered 1 hour ago Carlo 738

4

votes

4

answers

4k

views

$m(\alpha E)=\alpha m(E)$ ? for every lebesgue measurable set and $\alpha >0$

real-analysis measure-theory

modified 1 hour ago Matematleta 21.1k

2

votes

1

answer

36

views

An isomorphism related to Fontaine's periods rings

algebraic-geometry algebraic-number-theory p-adic-number-theory galois-representations

answered 1 hour ago Torsten Schoeneberg 10.1k

0

votes

0

answers

8

views

Pricing options on several underlying assets using FDM

stochastic-processes stochastic-differential-equations finite-differences finite-difference-methods

asked 1 hour ago Natalie_eds 1

5

votes

0

answers

204

views

+500

Help with the proof that $E\subset \mathbb{R}$ with finite perimeter and area has to be equal to the finite union of bounded intervals

functional-analysis geometry analysis geometric-measure-theory

modified 1 hour ago Daniele Tampieri 4,012

0

votes

0

answers

5

views

Recurrent and Transient random walks on integer grids

probability-theory stochastic-processes random-walk binomial-distribution

asked 1 hour ago DarthWader 1

0

votes

0

answers

13

views

Calculus: Early Transcendentals, 7th ed(stewart)-chapter 12 problems plus exercise 3

geometry euclidean-geometry analytic-geometry

asked 1 hour ago salvador madrigal 1

3

votes

2

answers

59

views

Combinatorial identity: $\sum\limits_{k=0}^{i\land j}\binom ik(-1)^k\binom{i+j-k}i=1$

combinatorics summation binomial-coefficients birth-death-process

answered 1 hour ago Marko Riedel 48.1k

0

votes

0

answers

14

views

finding the unique maximizer of the function

real-analysis functions optimization

modified 1 hour ago user229519 51

1

vote

0

answers

10

views

How to calculate the joint probability: $\Pr \left( \tfrac{g_1}{g_3} \geq \theta_1, \tfrac{g_2}{g_3} \geq \theta_2, g_3 > \theta_3 \right)$?

probability indefinite-integrals density-function exponential-distribution

modified 2 hours ago Raskolnikov 13.6k

2

votes

1

answer

20

views

Parametric curve of a spiral with straight and semicircular parts

geometry parametric

modified 2 hours ago Blue 58k

0

votes

1

answer

15

views

Finding a point in a metric space

metric-spaces approximation median

answered 2 hours ago Exodd 7,171

0

votes

0

answers

11

views

Linear Programming approach for downtime minimization

optimization linear-programming

asked 2 hours ago alexpwns 1

1

vote

0

answers

20

views

$\int_{C}((y^{2}-z^{2})dx + 2yzdy-x^{2}dz)$ is my result correct?

calculus integration line-integrals

modified 2 hours ago Sangchul Lee 114k

2

votes

0

answers

7

views

Real analytic set on a compact domain, no zeros on the boundary - isolated points only?

real-analysis systems-of-equations compactness

asked 2 hours ago rudi_ 21

0

votes

0

answers

4

views

what is the equation for the path of the water if the maximum height of the water must be 4 feet

quadratics

asked 2 hours ago Marcella Demulling 1

0

votes

0

answers

8

views

Time average of perturbation energy and intensity in acoustics

calculus fluid-dynamics

asked 2 hours ago SpaghettiMonsterMan 45

0

votes

2

answers

59

views

Linear Algebra Textbook for Reference?

linear-algebra reference-request online-resources

modified 2 hours ago failedstatistician 143

0

votes

0

answers

14

views

Exercice in Miranda's Book , divisors on Algebraic Curves

riemann-surfaces divisors-algebraic-geometry

modified 2 hours ago Something 1,732

2

votes

1

answer

51

views

Intuition behind Willmore energy

differential-geometry

modified 2 hours ago coldwave 11

0

votes

0

answers

4

views

Embedding of a Riemann surface in $\mathbb{P}^n$ by a very ample divisor

riemann-surfaces divisors-algebraic-geometry

asked 2 hours ago Something 1,732

1

vote

0

answers

18

views

Fourier series solution to the one dimensional Fokker-Planck equation

probability partial-differential-equations fourier-series

modified 2 hours ago Leucippus 21.9k

1

vote

0

answers

11

views

“Linear approximation” to topological sheaf $\mathrm{Imm}(-,N)$

algebraic-topology manifolds homotopy-theory

asked 2 hours ago Andres Mejia 18.4k

1

vote

0

answers

9

views

If $X_t$ is a martingale, does this mean that $E[d X_t | X_t] = 0$

stochastic-processes brownian-motion martingales random-walk

asked 3 hours ago s5s 281

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