A positive Bézout's identity
29084
Largest integer that can't be represented as a non-negative linear combination of $m, n = mn - m - n$? Why?
46875
The identity morphism in $\mathbf{Set}$ is the identity function
67820
Showing that $(A_{ij})=\left(\frac1{1+x_i+x_j}\right)$ is positive semidefinite
157733
Are positive real numbers $x,y$ allowed to be taken out during this proof?
56311
Proving $(1+a_{2})^{2}(1+a_{3})^{3}\cdots(1+a_{n})^{n}\ge n^n$ for positive reals $a_2,\ldots, a_n$ whose product is $1$
46825
The identity det(A) = exp(Tr(ln(A)) for A general
150674
Uniqueness in existence of a bilinear form
33673
Proving $N(x) = (A(x,x))^\frac12$ is a norm in $V$ given that A is a positive definite bilinear form
140140
An identity which applies to all of the natural numbers
776
Entire function with positive real part is constant (no Picard)
31076
Roots of unity filter, identity involving $\sum_{k \ge 0} \binom{n}{3k}$
56818
Prove that if $A$ is positive, then $\exists\;\alpha>0$ such that $\langle Ax, x \rangle\geq \alpha|x|^2$ for $x\in\Bbb{R}^n$
122490
Proof of Parseval's identity
117418
Showing that the image of a function is $\mathbb{C}$ if it satisfies a nice functional equation
56612
Proof of $\gcd(a,b)=ax+by\ $ [Bezout's identity]
120010
Show that $\aleph_{\alpha}^{\aleph_{1}} = \aleph_{\alpha}^{\aleph_{0}}\cdot 2^{\aleph_1}$
7457
Prove that $J^+AJ$ has positive eigenvalues