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Lucas Alanis
  • Member for 9 years, 7 months
  • Last seen more than a week ago
  • Athens, Greece
37 votes
1 answer
30k views

Proof for why a matrix multiplied by its transpose is positive semidefinite

6 votes
4 answers
1k views

How to compute the following integral?

5 votes
3 answers
3k views

What does "within $x$% of $y$" mean?

5 votes
2 answers
752 views

How to proof the following Gronwall type inequality?

4 votes
1 answer
2k views

How to find the maximal interval of existence of the solution for the following initial value problem?

4 votes
2 answers
8k views

Proof that an $n \times n$ real symmetric matrix has $n$ real eigenvalues [closed]

4 votes
1 answer
451 views

How to find the following derivative?

4 votes
3 answers
1k views

Trying to understand the meaning of symmetry

4 votes
1 answer
18k views

How to find the central angle of a circle?

4 votes
3 answers
268 views

Limits and continuous functions

4 votes
3 answers
290 views

Why do we choose $3$ to be positive after $\sqrt{9 - x^2}$ in the following substitution?

3 votes
3 answers
208 views

How to compute the following summation?

3 votes
2 answers
2k views

How to find a solution(s) when given two equations of two variables?

3 votes
1 answer
277 views

How can the variance of data be represented as this product of the principal direction and the covariance matrix?

2 votes
1 answer
290 views

How to find the inverse Laplace transform of this?

2 votes
3 answers
252 views

Question about absolute value in inequalities

2 votes
1 answer
471 views

The time it takes an object to go through a hole through the Earth's center

2 votes
2 answers
961 views

Question about additivity of integration on intervals

2 votes
2 answers
69 views

How to figure the size of the following vector set?

2 votes
2 answers
58 views

If $a = \mathrm {sup}\ B$, how to show that the following holds?

2 votes
1 answer
4k views

Is $\mathbb Q \times \mathbb Q $ a denumerable set? [duplicate]

2 votes
3 answers
140 views

,How to show that a set is empty?

2 votes
1 answer
105 views

How to show that $[\xi, \eta ]$ is equal to the intersection of the following closed, nested, and bounded intervals?

2 votes
1 answer
52 views

What would occur after the summation of two sequences that diverge?

1 vote
1 answer
47 views

How to show that the following sequence is bounded and decreasing?

1 vote
3 answers
97 views

How to show that $\frac {1}{2^n} \lt \frac {1}{n}$ for all $n \in \mathbb N$?

1 vote
1 answer
204 views

Is it possible to show that the addition of two Cauchy sequences in $\mathbb R^n$ is also Cauchy for any metric?

1 vote
2 answers
101 views

Trouble understanding the proof for linear independency of a basis for a linear transformation

1 vote
3 answers
2k views

Relationship between the eigenvalues of $A^T A$ and the maximum eigenvalue of $A$

1 vote
2 answers
5k views

How to calculate the volume obtained by rotating the following around the x axis?