User Francisco José Letterio

41 votes

2 answers

3k views

Do you lose solutions when differentiating to solve an integral equation?

ordinary-differential-equations integral-equations

asked Sep 13, 2021 at 20:59

29 votes

5 answers

4k views

Why must be the additive and multiplicative identities in a field be different?

abstract-algebra field-theory

asked Nov 16, 2017 at 17:36

6 votes

1 answer

441 views

Help proving that a polynomial has n roots and that they're all different

polynomials

asked Nov 19, 2017 at 2:41

5 votes

1 answer

93 views

Whst's the relationship between these two theorems? [duplicate]

general-topology logic

asked Dec 28, 2019 at 22:58

4 votes

0 answers

58 views

Counting all $9 \times 8$ matrices with two restrictions (checking if I'm right)

combinatorics discrete-mathematics proof-verification

asked Dec 15, 2017 at 22:47

3 votes

2 answers

132 views

Is there an intuitive way of thinking why a rearranged conditionally convergent series yields different results?

sequences-and-series intuition conditional-convergence

asked Jun 4, 2018 at 10:27

3 votes

1 answer

69 views

Let$A$ be an open, dense set in $\mathbb R^n$. Prove that $A + A = \mathbb R^n$

general-topology real-numbers

asked Dec 4, 2020 at 5:35

3 votes

1 answer

38 views

Prove that given a finite set $A$ in the plane, there is an infinite family of points that have the same distance ($d_{\infty}$) to each point in A

geometry metric-spaces

asked Aug 5, 2021 at 5:43

3 votes

1 answer

521 views

Why does this identity hold for Fejér Kernels?

fourier-analysis fourier-series fejer-kernel

asked Apr 20, 2019 at 0:46

3 votes

2 answers

147 views

Let X be a set with 30 elements. How many equivalence relations can be defined on X if every class of the relation must have exactly 6 elements?

combinatorics discrete-mathematics permutations

asked Dec 13, 2017 at 20:03

2 votes

2 answers

94 views

Finding the limit as x approaches 1 of $\sum \frac {(-1)^{n+1}}{n} x^n$

real-analysis uniform-convergence

asked Dec 8, 2020 at 5:31

2 votes

1 answer

41 views

How to prove $x^2f -(x+1)f' = x^2g -(x+1)g' \Rightarrow f = g$ for polynomials f,g with rational coefficients

polynomials

asked Mar 1, 2020 at 6:36

2 votes

1 answer

39 views

How to find a Graph's $K_v$?

discrete-mathematics graph-theory graph-connectivity

asked Apr 10, 2018 at 19:50

2 votes

4 answers

1k views

How to better prove this statement? Let G be a graph with $n$ vertices and $k > {n-1 \choose 2}$ edges. Then G is connected

discrete-mathematics graph-theory

asked Apr 4, 2018 at 1:55

2 votes

1 answer

527 views

What are the eigenvectors of a recurrence relation?

linear-algebra eigenvalues-eigenvectors recurrence-relations self-learning

asked Oct 26, 2017 at 13:23

2 votes

0 answers

42 views

Is there any way to predict the amount of "carries" one could get by doing a sum?

arithmetic computer-arithmetic

asked Oct 31, 2017 at 14:49

2 votes

0 answers

366 views

Proving this Legendre's Formula [duplicate]

elementary-number-theory number-systems

asked Oct 6, 2017 at 18:13

1 vote

0 answers

53 views

Prove that the sum of digits of n, when n is written in base 2, is equal to the sum of digits of 2n

elementary-number-theory

asked Oct 6, 2017 at 21:24

1 vote

3 answers

113 views

Solve $\begin{cases}8x^{329} + 6x^{628} -2 \equiv 1 \pmod {15}\\(x^{1328} - 4)^2 \equiv 0 \pmod 7\end{cases}$ .

modular-arithmetic

asked Sep 20, 2017 at 23:01

1 vote

2 answers

631 views

Prove that the following polynomial has no multiple roots [duplicate]

polynomials roots

asked Oct 17, 2017 at 20:24

1 vote

1 answer

29 views

Distributing 10 different folders between 7 people such that John gets at least 1 folder

combinatorics

asked Sep 29, 2017 at 22:15

1 vote

1 answer

1k views

How many ways are there to park cars and motorcycles in a parking lot with 100 spaces?

combinatorics recurrence-relations

asked Oct 30, 2017 at 18:14

1 vote

1 answer

129 views

Is my reasoning correct? (using the stars and bars method)

combinatorics discrete-mathematics

asked Dec 13, 2017 at 0:20

1 vote

2 answers

102 views

Proving that the limit at $(0,-1)$ does not exist

real-analysis limits multivariable-calculus

asked Mar 10, 2018 at 21:20

1 vote

1 answer

73 views

Help with identity proof using sum manipulations

summation alternative-proof

asked Dec 28, 2017 at 4:57

1 vote

0 answers

41 views

Can we find a solution for this indefinite sum using finite calculus?

discrete-mathematics discrete-calculus

asked Jan 1, 2018 at 20:51

1 vote

0 answers

66 views

Help identifying mistake during sum manipulation

summation discrete-calculus

asked Feb 2, 2018 at 1:23

1 vote

2 answers

183 views

Prove that for a sufficiently differentiable $f$, if $f(x,y) = g(x+y)$ then its partial derivatives are equal

multivariable-calculus partial-derivative

asked Apr 10, 2018 at 21:13

1 vote

0 answers

68 views

Is there a name for this notion in mathematics?

combinatorics

asked Apr 23, 2018 at 4:39

1 vote

1 answer

48 views

Which of these two definitions is wrong?

vector-analysis vector-fields

asked Apr 25, 2018 at 21:59

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65 Questions

Do you lose solutions when differentiating to solve an integral equation?

Why must be the additive and multiplicative identities in a field be different?

Help proving that a polynomial has n roots and that they're all different

Whst's the relationship between these two theorems? [duplicate]

Counting all $9 \times 8$ matrices with two restrictions (checking if I'm right)

Is there an intuitive way of thinking why a rearranged conditionally convergent series yields different results?

Let$A$ be an open, dense set in $\mathbb R^n$. Prove that $A + A = \mathbb R^n$

Prove that given a finite set $A$ in the plane, there is an infinite family of points that have the same distance ($d_{\infty}$) to each point in A

Why does this identity hold for Fejér Kernels?

Let X be a set with 30 elements. How many equivalence relations can be defined on X if every class of the relation must have exactly 6 elements?

Finding the limit as x approaches 1 of $\sum \frac {(-1)^{n+1}}{n} x^n$

How to prove $x^2f -(x+1)f' = x^2g -(x+1)g' \Rightarrow f = g$ for polynomials f,g with rational coefficients

How to find a Graph's $K_v$?

How to better prove this statement? Let G be a graph with $n$ vertices and $k > {n-1 \choose 2}$ edges. Then G is connected

What are the eigenvectors of a recurrence relation?

Is there any way to predict the amount of "carries" one could get by doing a sum?

Proving this Legendre's Formula [duplicate]

Prove that the sum of digits of n, when n is written in base 2, is equal to the sum of digits of 2n

Solve $\begin{cases}8x^{329} + 6x^{628} -2 \equiv 1 \pmod {15}\\(x^{1328} - 4)^2 \equiv 0 \pmod 7\end{cases}$ .

Prove that the following polynomial has no multiple roots [duplicate]

Distributing 10 different folders between 7 people such that John gets at least 1 folder

How many ways are there to park cars and motorcycles in a parking lot with 100 spaces?

Is my reasoning correct? (using the stars and bars method)

Proving that the limit at $(0,-1)$ does not exist

Help with identity proof using sum manipulations

Can we find a solution for this indefinite sum using finite calculus?

Help identifying mistake during sum manipulation

Prove that for a sufficiently differentiable $f$, if $f(x,y) = g(x+y)$ then its partial derivatives are equal

Is there a name for this notion in mathematics?

Which of these two definitions is wrong?