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nyorkr23
  • Member for 8 years, 2 months
  • Last seen more than 7 years ago
6 votes
1 answer
4k views

How do I prove the uniqueness of additive identity?

5 votes
2 answers
243 views

21 points on circumference of a circle must have at least 100 pairs separated by 120+ degrees.

3 votes
3 answers
154 views

An induction problem that I can't think of an approach.

3 votes
1 answer
450 views

Determine all maximal planar graphs, where one-third of their vertices have degree $3$, one-third have degree $4$, and one third have degree $5$.

2 votes
1 answer
67 views

If $a$ and $b$ are positive rational numbers with $a < b$, show that $\frac{1}{a} >\frac {1}{b}$

2 votes
2 answers
600 views

Establish by mathematical induction that a set having $n$ elements has $2^n$ subsets.

2 votes
2 answers
1k views

Let $G$ be a simple graph on $10$ vertices and $38$ edges. Prove that $G$ contains $K_4$ as an induced subgraph.

1 vote
1 answer
3k views

Prove that every edge-coloring of $K_{17}$ with $3$ colors contains a monochromatic $K_3$. [duplicate]

1 vote
2 answers
2k views

Prove that the sum of the degrees in the interior angles of a polygon with $n$ sides is $180(n – 2)°$.

1 vote
2 answers
2k views

Prove that every triangle-free graph on n vertices has chromatic number at most 2√n.

1 vote
3 answers
578 views

If $p$ and $q$ are positive prime numbers such that $p$ is divisible by $q$, show that $p = q$.

1 vote
2 answers
478 views

Prove that $[a]=[b]$ iff $a\sim b$.

1 vote
1 answer
589 views

Let $G$ be a $k$-regular bipartite graph, $k \ge 2$. Prove that every edge of $G$ appears in some perfect matcing in $G$. Is this proof correct?

1 vote
1 answer
2k views

Let $W_n$ be the wheel graph on $n+1$ vertices. Find $χ(W_n;k)$. [duplicate]

1 vote
2 answers
151 views

A prime number problem.

1 vote
1 answer
2k views

How to show two integers are coprime in a linear combination?

1 vote
1 answer
258 views

Show that if $a$ is a divisor of $bc$ and $(a, b) = 1$, then $a$ is a divisor of $c$. [duplicate]

1 vote
1 answer
104 views

For each positive integer $n$ , show that there are more than $n$ positive primes.

1 vote
1 answer
58 views

What part of integration am I missing?

1 vote
2 answers
110 views

How do i integrate this? Hyperbolic substitution?

0 votes
1 answer
44 views

How do I find triple integrals?

0 votes
2 answers
2k views

Prove that there do not exist nonzero integers $a$ and $b$ such that $a^2=3b^2$. [duplicate]

0 votes
0 answers
117 views

Let $Z$ be the set of all integers, and define $a\equiv b$ to mean that $a-b$ has $5$ as a factor.

0 votes
1 answer
1k views

How to find the number of faces of a rhombicosadodecahedron?

0 votes
2 answers
346 views

Prove that the nonzero element $[a]$ of the ring $ Z /(n)$ has a multiplicative inverse iff $a$ and $n$ are relatively prime.

0 votes
2 answers
2k views

How to prove the uniqueness of multiplicative identity?

0 votes
0 answers
65 views

Find the relative extrema of $f|_S$

0 votes
2 answers
69 views

Use the rule for differentiating a product to prove that the derivative of $x^n$ is $nx^{n-1}$ for all $n∈N$.

0 votes
2 answers
144 views

If $a$ and $b$ are nonzero integers such that each is a divisor of the other, show that $a = ± b$ .

0 votes
1 answer
1k views

How to draw K1,3 and C5 as a cartesian product?