User xenon - Mathematics Stack Exchange

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	793 reputation	bio	website		visits	member for	1 year, 11 months
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3

7

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4

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Show that $\operatorname{rank}(A+B) \leq \operatorname{rank}(A) + \operatorname{rank}(B)$

mar 6 at 3:46 Sugata Adhya 1,546

7

votes

4

answers

886

views

Determining if a quadratic is always positive

homework calculus inequality quadratic-forms

aug 17 '11 at 18:38 David Speyer 18.5k

6

votes

4

answers

206

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Given $A^2+cA+cI=0$, how to find inverse of $A+(c-1)I$?

linear-algebra matrices

sep 26 '11 at 0:52 Pierre-Yves Gaillard 8,477

1

6

votes

1

answer

157

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Getting the determinant value of the original matrix from its upper triangular matrix

linear-algebra matrices

jul 1 '11 at 15:01 BenjaLim 16.6k

5

votes

2

answers

216

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Reason for reversing the order when transpose and inverse of a group of matrices

homework linear-algebra matrices

jul 6 '11 at 0:36 ncmathsadist 16.9k

5

votes

2

answers

73

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Will any value of a free variable satisfy a system of equation?

linear-algebra matrices

jun 28 '11 at 20:42 platinumtucan 821

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5

votes

1

answer

1

kviews

Properties of a matrix whose row vectors are dependent

linear-algebra matrices vector-spaces

jun 27 '11 at 18:07 xenon 793

4

votes

1

answer

454

views

Finding normal vectors of polygons

geometry vector-spaces

oct 6 '11 at 2:13 xpda 191

1

4

votes

2

answers

1

kviews

Why composite transformations are multiplied to the right side?

linear-algebra matrices transformation

sep 18 '11 at 10:34 Hauke Strasdat 727

1

3

votes

1

answer

2

kviews

How do I determine if the vectors lie on a plane in an $N\times N$ matrix?

linear-algebra matrices vector-spaces

apr 3 at 4:59 Stahl 3,587

3

votes

2

answers

200

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What is an intuitive meaning of $E(\overline { X } )$ and $Var(\overline { X } )$?

probability statistics

mar 24 '12 at 17:57 Michael Hardy 47.7k

3

votes

3

answers

143

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How come the columns of a matrix can form its nullspace?

linear-algebra matrices

nov 25 '11 at 4:25 Community♦ 1

3

votes

3

answers

2

kviews

Getting the inverse of a lower/upper triangular matrix

linear-algebra matrices

sep 25 '11 at 16:35 ziyuang 749

1

3

votes

2

answers

64

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Proving $S+T$ is a subspace of $\mathbb{R}^{n}$

linear-algebra matrices

sep 24 '11 at 16:02 xenon 793

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3

votes

3

answers

283

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How to multiply a matrix of block matrices?

linear-algebra matrices

sep 15 '11 at 9:06 Community♦ 1

3

votes

2

answers

191

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Deriving the inverse of $\mathbf{I}$+Idempotent matrix

linear-algebra matrices

aug 22 '11 at 10:09 Pierre-Yves Gaillard 8,477

3

votes

2

answers

136

views

Why eigenvectors basis then transformation matrix is $\Lambda$?

homework linear-algebra matrices eigenvalues

aug 19 '11 at 17:29 Arturo Magidin 158k

3

votes

3

answers

697

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$A^{T}A$ positive definite then A is invertible?

homework linear-algebra matrices

aug 6 '11 at 17:41 Community♦ 1

3

votes

2

answers

137

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Creating a matrix of rank r from r number of rank 1 matrices?

linear-algebra matrices

jul 4 '11 at 20:20 Thomas Santoli 96

1

3

votes

1

answer

126

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Deriving equation of plane from reduced row echelon form

linear-algebra matrices

jun 29 '11 at 20:17 Arturo Magidin 158k

2

votes

1

answer

2

kviews

Finding probability $P(X+Y < 1)$ with CDF

probability statistics

jan 14 at 1:47 Ralph 1

2

votes

2

answers

170

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“Splitting” determinant of a matrix

homework linear-algebra matrices

jun 13 '12 at 1:10 mixedmath♦ 27.2k

2

votes

1

answer

231

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Find probabilities of winning in a modified version of Monty Hall Problem

probability statistics

mar 13 '12 at 22:02 Vadim 1,831

2

votes

1

answer

196

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Finding $P(A|B)$ with conditional probability formula

probability

jan 17 '12 at 6:32 Isaac 21.1k

2

votes

2

answers

84

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Finding all vectors of $\vec{y}$ such that $\operatorname{span} \left \{ \vec{v_1}, \vec{v_2}, \vec{y} \right \} = \mathbb{R^3}$

linear-algebra

nov 20 '11 at 17:18 Michael Hardy 47.7k

2

votes

2

answers

117

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Showing $AS$ is orthogonal if $A$ and $S$ are orthogonal

linear-algebra matrices

nov 13 '11 at 16:03 M Turgeon 4,541

1

2

votes

2

answers

232

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Finding the column space from nullspace and particular solution

linear-algebra matrices

oct 22 '11 at 19:16 Arturo Magidin 158k

2

votes

2

answers

490

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How is diagonal matrices a subspace of upper triangular matrices?

linear-algebra matrices

sep 24 '11 at 13:34 André Nicolas 160k

2

votes

2

answers

1

kviews

Column Vectors orthogonal implies Row Vectors also orthogonal?

homework linear-algebra matrices

jul 20 '11 at 19:49 ncmathsadist 16.9k

1

vote

1

answer

194

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Why Binomial Distribution formula includes the “not-happening” probability?

probability statistics probability-distributions

apr 19 at 9:25 ayisam tc 1

xenon

56 Questions