User Lucas Alanis

37 votes

1 answer

34k views

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

asked Oct 3, 2015 at 23:26

6 votes

4 answers

1k views

How to compute the following integral?

asked Jan 3, 2013 at 0:58

5 votes

3 answers

3k views

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

asked Apr 4, 2016 at 23:00

5 votes

2 answers

780 views

How to proof the following Gronwall type inequality?

asked Nov 20, 2014 at 19:14

4 votes

1 answer

2k views

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

asked Nov 21, 2014 at 1:39

4 votes

2 answers

8k views

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

asked Oct 2, 2015 at 1:13

4 votes

1 answer

500 views

How to find the following derivative?

asked Jan 14, 2013 at 13:33

4 votes

3 answers

1k views

Trying to understand the meaning of symmetry

asked May 2, 2013 at 3:28

4 votes

1 answer

18k views

How to find the central angle of a circle?

asked Mar 8, 2013 at 4:42

4 votes

3 answers

326 views

Limits and continuous functions

asked Jun 2, 2013 at 4:28

4 votes

3 answers

309 views

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

asked Jan 1, 2013 at 22:08

3 votes

3 answers

214 views

How to compute the following summation?

asked Sep 10, 2014 at 1:48

3 votes

2 answers

3k views

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

asked Jun 15, 2013 at 19:43

3 votes

1 answer

303 views

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

asked Sep 19, 2015 at 20:22

2 votes

1 answer

314 views

How to find the inverse Laplace transform of this?

asked Oct 15, 2015 at 12:53

2 votes

3 answers

285 views

Question about absolute value in inequalities

asked Apr 23, 2013 at 17:30

2 votes

1 answer

492 views

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

asked Sep 17, 2013 at 15:46

2 votes

2 answers

1k views

Question about additivity of integration on intervals

asked Jan 30, 2013 at 4:26

2 votes

2 answers

70 views

How to figure the size of the following vector set?

asked Sep 9, 2014 at 3:25

2 votes

2 answers

58 views

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

asked Feb 17, 2014 at 5:14

2 votes

1 answer

4k views

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

asked Feb 5, 2014 at 4:07

2 votes

3 answers

147 views

,How to show that a set is empty?

asked Feb 9, 2014 at 2:57

2 votes

1 answer

122 views

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

asked Feb 18, 2014 at 4:11

2 votes

1 answer

54 views

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

asked Feb 26, 2014 at 8:52

1 vote

1 answer

50 views

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

asked Mar 8, 2014 at 20:49

1 vote

3 answers

97 views

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

asked Feb 18, 2014 at 0:34

1 vote

1 answer

209 views

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

asked Oct 4, 2014 at 0:31

1 vote

2 answers

105 views

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

asked Oct 31, 2014 at 21:52

1 vote

3 answers

2k views

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

asked Nov 7, 2014 at 4:03

1 vote

2 answers

5k views

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

asked Jan 4, 2013 at 7:46

Stack Exchange Network

61 Questions

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

How to compute the following integral?

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

How to proof the following Gronwall type inequality?

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

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

How to find the following derivative?

Trying to understand the meaning of symmetry

How to find the central angle of a circle?

Limits and continuous functions

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

How to compute the following summation?

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

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

How to find the inverse Laplace transform of this?

Question about absolute value in inequalities

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

Question about additivity of integration on intervals

How to figure the size of the following vector set?

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

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

,How to show that a set is empty?

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

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

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

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

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

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

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

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