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q.Then
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21 votes
4 answers
30k views

Proof that any linear system cannot have exactly 2 solutions.

12 votes
3 answers
3k views

mod Distributive Law, factoring $\!\!\bmod\!\!:$ $\ ab\bmod ac = a(b\bmod c)$

9 votes
1 answer
1k views

Collatz $4n+1$ rule?

5 votes
3 answers
4k views

Proof of no primes such that $x^2 + y^2 = z^2$ [duplicate]

4 votes
1 answer
3k views

If two finite groups have the same number of elements of the same order, does this necessarily imply they are isomorphic? [duplicate]

4 votes
2 answers
600 views

What is the precise definition of a group action that is a symmetry?

4 votes
3 answers
224 views

How do I solve $18^{{20}^{19}}$ divided by 7?

4 votes
1 answer
658 views

If $\omega$ is primitive nth root of unity, then does $|\text{Gal}(\mathbb{Q}(\omega)/\mathbb{Q})| = n - 1$?

4 votes
2 answers
8k views

Finding the order of an element in the group of integers modulo n with addition

4 votes
3 answers
8k views

Prove existence of multiplicative inverse modulo p when p is prime

3 votes
1 answer
662 views

Clarification on the Wronskian

3 votes
1 answer
60 views

Confused as to why $x^2 \equiv 1 \pmod p$ has at most 2 solutions when $p$ is an odd prime

2 votes
2 answers
329 views

If $a$ is a primitive root modulo $p$, then $(p-1) | ord(a)$ in $\mathbb{Z}/p^e\mathbb{Z}$

2 votes
1 answer
566 views

Proof that there are countable many algebraic numbers

2 votes
3 answers
12k views

How many elements of order 5 are there in $S_7$ [duplicate]

2 votes
2 answers
6k views

If Ax = 0 for every x in $R^n$, A is a zero matrix [duplicate]

2 votes
2 answers
197 views

How many arrangements can a team of 8 students have such at all of them have their birthdays in 2 days (but not all on one day)

2 votes
1 answer
689 views

How can I generalize this?

2 votes
1 answer
1k views

Definition of matrix norm induced by vector $p$-norm

1 vote
2 answers
35 views

Finding dimension mathematically for simple equations

1 vote
1 answer
1k views

How to find eigenvalues for T without given a matrix

1 vote
2 answers
499 views

Eigenvalues for $T = T^2$

1 vote
1 answer
366 views

Why does the additive inverse not follow

1 vote
3 answers
57 views

Justification for solving modular congruencies

1 vote
2 answers
299 views

What are the units of $\mathbb{R}[x]/\langle x^2 + 1\rangle$?

1 vote
1 answer
1k views

An algebraic simple extension has finite degree

0 votes
1 answer
622 views

How many automorphisms are there in $\mathbb{Z}_{105}$ of order $12$?

0 votes
1 answer
64 views

$3x + 1 = 2^i$ only has integer solutions when $i$ is even

0 votes
3 answers
97 views

For what values is $x + y = z$ and $a^x + a^y = a^z$?

0 votes
3 answers
47 views

Explanation on derivation of this equation?