Orion_Pax's user avatar
Orion_Pax's user avatar
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Orion_Pax
  • Member for 1 year, 5 months
  • Last seen more than a month ago
433 votes
14 answers
357k views

Fourier transform for dummies

370 votes
20 answers
45k views

Find five positive integers whose reciprocals sum to $1$

  • 4,465
180 votes
4 answers
65k views

Overview of basic results about images and preimages

173 votes
2 answers
100k views

Discontinuous derivative. [duplicate]

  • 1,847
161 votes
21 answers
56k views

Looking for an intuitive explanation why the row rank is equal to the column rank for a matrix

  • 1,871
136 votes
10 answers
155k views

Physical meaning of the null space of a matrix

  • 12.9k
122 votes
8 answers
614k views

What is the difference between independent and mutually exclusive events?

  • 1,393
118 votes
9 answers
6k views

Probability that a stick randomly broken in five places can form a tetrahedron

118 votes
8 answers
76k views

Why is the derivative of a circle's area its perimeter (and similarly for spheres)?

  • 8,709
109 votes
11 answers
184k views

Why is the volume of a cone one third of the volume of a cylinder?

  • 8,709
98 votes
15 answers
84k views

How to prove that exponential grows faster than polynomial?

  • 6,687
96 votes
4 answers
64k views

Importance of matrix rank

  • 2,461
82 votes
11 answers
23k views

Logic problem: Identifying poisoned wines out of a sample, minimizing test subjects with constraints

  • 13.8k
81 votes
7 answers
173k views

What is the equation for a 3D line?

  • 22.4k
73 votes
11 answers
178k views

How to show that $\det(AB) =\det(A) \det(B)$?

  • 2,526
66 votes
6 answers
21k views

Why does $\tan^{-1}(1)+\tan^{-1}(2)+\tan^{-1}(3)=\pi$?

63 votes
5 answers
32k views

Choose a random number between $0$ and $1$ and record its value. Keep doing it until the sum of the numbers exceeds $1$. How many tries do we need?

  • 837
63 votes
1 answer
1k views

How to find a total order with constrained comparisons

56 votes
1 answer
92k views

Why is the absolute value function not differentiable at $x=0$?

52 votes
7 answers
78k views

Why does an infinite limit not exist?

  • 10.1k
51 votes
13 answers
144k views

What is the solution of $\cos(x)=x$?

  • 905
49 votes
8 answers
5k views

Finite Sum $\sum\limits_{k=1}^{m-1}\frac{1}{\sin^2\frac{k\pi}{m}}$

  • 122k
46 votes
7 answers
19k views

What function can be differentiated twice, but not 3 times?

  • 563
45 votes
4 answers
2k views

Prove that $\int_0^1 \left| \frac{f^{''}(x)}{f(x)} \right| dx \geq4$.

  • 7,338
44 votes
5 answers
108k views

Limit of $x \log x$ as $x$ tends to $0^+$

  • 2,285
42 votes
7 answers
3k views

How to evaluate $\sum_{k=3}^{\infty} \frac{\ln (k)}{k^2 - 4}$?

  • 3,788
40 votes
7 answers
325k views

How to calculate the intersection of two planes?

  • 1,029
38 votes
5 answers
2k views

What other tricks and techniques can I use in integration?

38 votes
5 answers
6k views

Best strategy to pick a lock which opens if at least two of its three decimal digit wheels are dialed correctly?

  • 943
37 votes
2 answers
131k views

Proof for triangle inequality for vectors

  • 3,680
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