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walcher
  • Member for 8 years, 11 months
  • Last seen more than 7 years ago
20 votes

How to calculate the intersection of two planes?

19 votes

What's 4 times more likely than 80%?

19 votes
Accepted

If union and intersection of two subsets are connected, are the subsets connected?

15 votes

Is matrix $A^TA$ always symmetric?

9 votes

What exactly is standard basis?

7 votes

Using permutation or otherwise, prove that $\frac{(n^2)!}{(n!)^n}$ is an integer,where $n$ is a positive integer.

7 votes
Accepted

Question on "Absolute value "

7 votes
Accepted

Prove Taylor expansion with mean value theorem

6 votes
Accepted

Show that $A$ is similar to a diagonal matrix iff $b=c=d=e=f=g=0$

6 votes
Accepted

How can one go from "no roots" to "is irreducible" in this case?

6 votes
Accepted

How does definition of nowhere dense imply not dense in any subset?

6 votes

math fallacy problem: $-1= (-1)^3 = (-1)^{6/2} = \sqrt{(-1)^6}= 1$?

5 votes

Prove that $n + 2$ is odd where $n = 2k+1$ for some integer $k$

5 votes
Accepted

What is a Proper Signature for a Vector Space?

5 votes

How find this maximum $Aa^2+Bb^2+Cc^2$ if $a+b+c=1$

5 votes
Accepted

Transitiveness of set sizes

4 votes
Accepted

show that the group of $2\times 2$ invertible matrices is isomorphic to $S_{3}$

4 votes
Accepted

If a mapping from positive integers to a cyclic group fails to be injective, show that the group is finite

4 votes

Continuous differentiability implies Lipschitz continuity

4 votes
Accepted

Number of conjugates of $x \in G$ in $H \triangleleft G$

4 votes

Show that if $A$ is positive definite then $A + A^{-1} - 2I$ is positive semidefinite

3 votes
Accepted

singleton null vector set linearly dependent, but other singletons are linearly independent set

3 votes
Accepted

two outer angle are not equal

3 votes

Invariant factor decomposition, fundamental theorem of finite generated abelian groups

3 votes
Accepted

How I can define an equivalence relation?

3 votes

How to Prove: $|Z_1 + Z_2| \leq |Z_1| + |Z_2|$

3 votes
Accepted

How to prove this inequality in a metric space

3 votes
Accepted

$-\mathbb{N}$ is not bounded below, right?

3 votes

Algebraic closure of a field in the rational functional field is the field itself.

3 votes

Divisibility implications proof