Alex Jones's user avatar
Alex Jones's user avatar
Alex Jones's user avatar
Alex Jones
  • Member for 7 years, 9 months
  • Last seen this week
51 votes
Accepted

Why are algebraic structures preserved under intersection but not union?

44 votes

Can area of rectangle be greater than the square of its diagonal?

19 votes

Can differentiation be thought of as a function?

12 votes

Find the height of a bar, given the lengths of shadows cast by it and another bar

10 votes
Accepted

Why do PDE's seem so unnatural?

10 votes
Accepted

Proof that Markov Matrix has Eigenvalue of 1

10 votes

Why not include as a requirement that all functions must be continuous to be differentiable?

9 votes
Accepted

A non-linear coupled second order ODE for a geodesic

8 votes
Accepted

Does ...999.999... = 0?

8 votes

Does every vector have an additive inverse?

7 votes
Accepted

What's going on with this 5-line proof of Fermat's Last Theorem?

7 votes

What is the rigorous definition of $dy$ and $dx$?

6 votes

How many words (i.e. not "math" symbols") should I use in my proofs? ${}{}$

6 votes
Accepted

How to compute $\int\limits_{\mathbb{R}^3}\det D^2 u(\mathbf{r}) d\mathbf{r}$?

6 votes

What are the coordinates of red point?

6 votes

Why did I never learn about magmas?

6 votes

Can I use algebraic identities with matrices?

6 votes
Accepted

Deriving the equation of a parabola?

6 votes

Second order linear ODEs and analytic coefficients

5 votes
Accepted

SIR model (3 differential equations)

5 votes

Why are proofs not written as collections of logic symbols but are instead written in sentences?

5 votes

How is $y'=x^2+1$ a differential equation?

5 votes

Why does this description of vector spaces include so many tedious/ seemingly obvious criteria?

5 votes

Does absolute integrability imply integrability?

5 votes
Accepted

Do the simultaneous equations $4x+3y = 3$ and $6y-6 = -8x$ (which are basically the same equation) have "infinite solutions"?

5 votes

Orthogonal Projection Area of a 3-d Cube

5 votes
Accepted

A weird differentiation question.

5 votes

Differential Equation with Shifted Input

5 votes

Solving $f\left(x\right)+f\left(1/x\right)=K$

4 votes
Accepted

Would a point undefined on $f'(x)$ still be considered a critical point of $f(x)$ if it's undefined on $f(x)$?

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