New posts in proof-writing

Knowing that for any set of real numbers $x,y,z$, such that $x+y+z = 1$ the inequality $x^2+y^2+z^2 \ge \frac{1}{3}$ holds.

algebra-precalculus inequality proof-writing contest-math cauchy-schwarz-inequality

Question from Putnam '89: Primes of the form $101\ldots01$

elementary-number-theory prime-numbers proof-writing contest-math proof-verification

Is there such a thing as a mathematical thesaurus?

reference-request terminology proof-writing

How many faces of a solid can one "see"?

geometry proof-writing platonic-solids

Why are proofs written in first person plural? Were they ever written differently?

proof-writing math-history

Prove that if $a|b$ and $a|c$ then $a|(sb+tc)$ for all $s, t \in \mathbb{Z}$

proof-writing

Open rays form a subbasis for the order topology on $X$

general-topology proof-writing solution-verification

Prove by induction that $\sum_{r=0}^{n}\binom nr =2^k$

summation proof-writing solution-verification induction binomial-coefficients

Prove that a construction exists: is this a constructive proof or existential proof?

logic proof-writing proof-theory constructive-mathematics

If $f$ is continuous, nonnegative on $[a, b]$, show that $\int_{a}^{b} f(x) d(x) = 0$ iff $f(x) = 0$

real-analysis proof-verification proof-writing

IMO 1984: Prove that $0 ≤ yz + zx +xy −2xyz ≤ \frac {7}{27}$, where $x,y$ and $z$ are non-negative real numbers for which $x + y + z = 1.$

algebra-precalculus proof-verification inequality proof-writing contest-math

Proof that $\sqrt{5}$ is irrational

proof-writing

On proving that $\sum\limits_{n=1}^\infty \frac{n^{13}}{e^{2\pi n}-1}=\frac 1{24}$

sequences-and-series summation proof-writing pi summation-method

Critiques on proof showing $\sqrt{12}$ is irrational.

proof-writing irrational-numbers rationality-testing

Why do irrationality proofs of $\sqrt x$ not apply when $x$ is a perfect square?

elementary-number-theory proof-writing irrational-numbers rationality-testing

Show that for all real numbers $a$ and $b$, $\,\, ab \le (1/2)(a^2+b^2)$ [duplicate]

real-analysis inequality proof-writing

Finding the dimension of $S = \{B \in M_n \,|\, AB = BA\}$, where $A$ is a diagonalizable matrix

linear-algebra matrices vector-spaces proof-writing eigenvalues-eigenvectors

Prove $GL_2(\mathbb{Z}/2\mathbb{Z})$ is isomorphic to $S_3$

abstract-algebra proof-writing

Prove that if $2^n - 1$ is prime, then $n$ is prime for $n$ being a natural number

discrete-mathematics proof-writing

Tips for writing proofs

linear-algebra abstract-algebra soft-question proof-writing