User Luke Collins

7

19

votes

2

answers

1k

views

Is Pythagoras' Theorem a theorem?

geometry foundations

Mar 3 '20 at 21:32 Dr. Michael W. Ecker 163

12

votes

2

answers

2k

views

Notation: Is $(\Delta x)^2 = \Delta x^2$?

notation

Jan 10 '16 at 19:57 Mankind 12.3k

2

8

votes

4

answers

1k

views

Coefficients of the characteristic polynomial

linear-algebra matrices determinant

Jun 25 '19 at 22:09 J.G 4,329

7

votes

3

answers

163

views

Examples of functions with a removable discontinuity

calculus algebra-precalculus education

Dec 17 at 21:53 Don Thousand 11.3k

2

7

votes

5

answers

618

views

Better proof for $\frac{1+\cos x + \sin x}{1 - \cos x + \sin x} \equiv \frac{1+\cos x}{\sin x}$

trigonometry alternative-proof

Feb 23 '20 at 20:38 Luke Collins 7,620

2

7

votes

4

answers

298

views

Defining the Cosine Function from First Principles, intuitively

real-analysis geometry trigonometry

Jan 8 '19 at 3:56 David K 75.4k

2

7

votes

2

answers

5k

views

What is a homogeneous Differential Equation?

ordinary-differential-equations

Jan 28 '18 at 6:42 Community♦ 1

1

6

votes

1

answer

101

views

Is “lines remain lines” sufficient to characterise linearity in $\mathbb R^2$?

linear-algebra vector-spaces linear-transformations

Jan 15 at 1:03 Tesla Daybreak 578

2

6

votes

2

answers

675

views

In a ring, are cosets always additive?

abstract-algebra ring-theory

May 31 '17 at 23:35 Trevor Gunn 22.6k

2

4

votes

2

answers

182

views

“Old-Fashioned” O-level Maths Book

algebra-precalculus reference-request soft-question education book-recommendation

Jan 21 at 20:36 A-Level Student 4,118

2

4

votes

1

answer

88

views

Is it possible to express this sum in a closed form?

summation closed-form

Dec 3 '19 at 0:35 Luke Collins 7,620

3

4

votes

3

answers

141

views

Prove Nice Determinant Equations [duplicate]

linear-algebra matrices determinant

Dec 30 '18 at 10:38 Daniele Tampieri 6,709

4

votes

2

answers

373

views

Pattern in Isomorphisms between $\mathbb Z_m \times \mathbb Z_n$ and $\mathbb Z_{mn}$

group-theory prime-numbers direct-product

Nov 27 '17 at 23:52 lhf 200k

4

votes

2

answers

541

views

I know that any two left/right cosets are either equal or disjoint, but what about the sets of cosets?

group-theory

Nov 25 '17 at 16:20 G Tony Jacobs 28.6k

1

4

votes

1

answer

1k

views

Why does this prove that a curve is a straight line?

geometry differential-geometry proof-verification curvature

Jan 23 '17 at 16:28 Ted Shifrin 88.9k

3

votes

3

answers

63

views

Projection of linear combination of real numbers

calculus linear-algebra abstract-algebra number-theory elementary-number-theory

Dec 11 at 19:20 Raffaele 25.3k

1

3

votes

0

answers

75

views

Has anyone ever studied “triangular” equations?

algebra-precalculus soft-question recreational-mathematics triangular-numbers

Nov 30 at 22:16 J. W. Tanner 54.4k

3

votes

1

answer

56

views

Does a bounded well-ordered set have a maximum?

elementary-set-theory order-theory well-orders

Nov 21 at 10:29 Asaf Karagila♦ 350k

1

3

votes

3

answers

86

views

Polynomials such that $f_n(x+y, xy) = x^n + y^n$.

algebra-precalculus polynomials

Oct 30 at 0:54 Argon 23.4k

1

3

votes

1

answer

879

views

What is an exact differential equation?

ordinary-differential-equations

Aug 19 at 6:04 Community♦ 1

3

votes

2

answers

117

views

Is this proof that $\mathbb Q(\sqrt[4]{-5})/\mathbb Q$ is not normal correct?

abstract-algebra proof-verification galois-theory

Nov 16 '19 at 13:27 nguyen quang do 12.3k

3

votes

0

answers

114

views

Recursion-like sequences which are hard to relate recursively

discrete-mathematics induction recurrence-relations

May 11 '19 at 13:06 Luke Collins 7,620

2

3

votes

1

answer

3k

views

Classify all groups of order 75 [duplicate]

group-theory sylow-theory

Jan 28 '18 at 20:30 Dietrich Burde 106k

3

votes

1

answer

45

views

A Convention of Set Builder Notation

elementary-set-theory

Jan 13 '18 at 13:27 Asaf Karagila♦ 350k

1

3

votes

1

answer

289

views

Proof that an abelian group whose action has one orbit has a singleton stabiliser.

group-theory permutations

Nov 15 '17 at 19:49 James 8,442

3

votes

1

answer

94

views

Notation: Relabelling elements of a (finite) set

combinatorics notation

Nov 13 '17 at 8:02 Eike Schulte 1,131

3

votes

2

answers

3k

views

Is the multiplicative identity unique in a unit ring?

ring-theory

May 29 '17 at 23:57 rschwieb 131k

1

3

votes

1

answer

104

views

Number of ways of Sitting at Two tables

probability combinatorics combinations

Apr 13 '17 at 14:21 drhab 134k

3

votes

1

answer

392

views

How is this Taylor's Theorem?

calculus analysis taylor-expansion

Mar 9 '17 at 0:37 quantumkid 216

3

votes

1

answer

680

views

Proving that a limit of a piecewise constant function does not exist using $\epsilon$-$\delta$

real-analysis limits epsilon-delta

Dec 6 '16 at 22:58 ervx 11.6k

Stack Exchange Network

current community

your communities

more stack exchange communities

Next privilege

Next badge

99 Questions

Is Pythagoras' Theorem a theorem?

Notation: Is $(\Delta x)^2 = \Delta x^2$?

Coefficients of the characteristic polynomial

Examples of functions with a removable discontinuity

Better proof for $\frac{1+\cos x + \sin x}{1 - \cos x + \sin x} \equiv \frac{1+\cos x}{\sin x}$

Defining the Cosine Function from First Principles, intuitively

What is a homogeneous Differential Equation?

Is “lines remain lines” sufficient to characterise linearity in $\mathbb R^2$?

In a ring, are cosets always additive?

“Old-Fashioned” O-level Maths Book

Is it possible to express this sum in a closed form?

Prove Nice Determinant Equations [duplicate]

Pattern in Isomorphisms between $\mathbb Z_m \times \mathbb Z_n$ and $\mathbb Z_{mn}$

I know that any two left/right cosets are either equal or disjoint, but what about the sets of cosets?

Why does this prove that a curve is a straight line?

Projection of linear combination of real numbers

Has anyone ever studied “triangular” equations?

Does a bounded well-ordered set have a maximum?

Polynomials such that $f_n(x+y, xy) = x^n + y^n$.

What is an exact differential equation?

Is this proof that $\mathbb Q(\sqrt[4]{-5})/\mathbb Q$ is not normal correct?

Recursion-like sequences which are hard to relate recursively

Classify all groups of order 75 [duplicate]

A Convention of Set Builder Notation

Proof that an abelian group whose action has one orbit has a singleton stabiliser.

Notation: Relabelling elements of a (finite) set

Is the multiplicative identity unique in a unit ring?

Number of ways of Sitting at Two tables

How is this Taylor's Theorem?

Proving that a limit of a piecewise constant function does not exist using $\epsilon$-$\delta$