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nullgeppetto
  • Member for 8 years, 10 months
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1211 votes
26 answers
127k views

Is $\frac{\textrm{d}y}{\textrm{d}x}$ not a ratio?

  • 15.1k
792 votes
1 answer
43k views

A proof for $\dim(R[T])=\dim(R)+1$ without prime ideals?

738 votes
12 answers
209k views

Does $\pi$ contain all possible number combinations?

  • 7,381
369 votes
71 answers
79k views

'Obvious' theorems that are actually false

  • 11.1k
340 votes
11 answers
211k views

What is the importance of eigenvalues/eigenvectors?

  • 5,129
295 votes
21 answers
48k views

Really advanced techniques of integration (definite or indefinite)

  • 8,509
277 votes
4 answers
73k views

Norms Induced by Inner Products and the Parallelogram Law

277 votes
3 answers
15k views

How does one prove the determinant inequality $\det\left(6(A^3+B^3+C^3)+I_{n}\right)\ge 5^n\det(A^2+B^2+C^2)$?

275 votes
8 answers
62k views

Please explain the intuition behind the dual problem in optimization.

  • 48.5k
211 votes
22 answers
37k views

Is it faster to count to the infinite going one by one or two by two? [closed]

  • 1,615
202 votes
34 answers
40k views

List of interesting math videos / documentaries

193 votes
1 answer
7k views

Generalizing $\int_{0}^{1} \frac{\arctan\sqrt{x^{2} + 2}}{\sqrt{x^{2} + 2}} \, \frac{\operatorname dx}{x^{2}+1} = \frac{5\pi^{2}}{96}$

187 votes
12 answers
322k views

Inverse of the sum of matrices

186 votes
8 answers
196k views

Proof that the trace of a matrix is the sum of its eigenvalues

  • 5,750
183 votes
7 answers
284k views

Transpose of inverse vs inverse of transpose

  • 2,265
178 votes
12 answers
81k views

What is $dx$ in integration?

168 votes
9 answers
15k views

Why do people use "it is easy to prove"?

  • 865
167 votes
7 answers
90k views

Intuitively, what is the difference between Eigendecomposition and Singular Value Decomposition?

  • 12.7k
165 votes
8 answers
179k views

What is the difference between "singular value" and "eigenvalue"?

  • 1,659
159 votes
7 answers
32k views

Is Apple ipad / tablet good for mathematics students? [closed]

  • 2,964
159 votes
20 answers
20k views

How to distinguish between walking on a sphere and walking on a torus?

  • 2,415
155 votes
6 answers
217k views

Is the product of two Gaussian random variables also a Gaussian?

  • 3,964
151 votes
1 answer
12k views

Is the following matrix invertible?

  • 1,739
148 votes
2 answers
43k views

Examples of bijective map from $\mathbb{R}^3\rightarrow \mathbb{R}$

  • 31.5k
142 votes
1 answer
5k views

Identification of a curious function

  • 55.7k
133 votes
15 answers
79k views

Why is $1$ not a prime number?

  • 8,641
131 votes
10 answers
6k views

what is expected from a PhD student?

129 votes
20 answers
88k views

Real life applications of Topology

  • 2,879
118 votes
2 answers
82k views

Prove that simultaneously diagonalizable matrices commute

  • 3,210
117 votes
10 answers
12k views

Find the average of $\sin^{100} (x)$ in 5 minutes?

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