To Show that $T$ is singular
37813
If $T\colon \mathbb R^n \to \mathbb R^n $ linear and $T^2 = kT$
56983
Square of a function with an essential singularity
36090
$TT^*=T^2$, show that $T$ is self-adjoint
87494
$\operatorname{rank}(T^3) + \operatorname{rank}(T) \geq 2\operatorname{rank}(T^2)$ for finite-dimensional $V$
151553
Big-O proof showing that t(n) is O(1)
126197
Prove that $T$ has a cyclic vector iff its minimal and characteristic polynomials are the same
63104
Dual cone of $K = \{(x,t) \mid \| \boldsymbol{x} \|_1 \le t \}$
132311
T$\mathbb{S}^{n} \times \mathbb{R}$ is diffeomorphic to $\mathbb{S}^{n}\times \mathbb{R}^{n+1}$
6514
Prove $T$ has at most two distinct eigenvalues
34702
Show $|A + uv^T| = (1 + v^T A^{-1} u) |A|$
29055
How to prove that $c_0I+c_1A+..+C_nA^n$ is singular if $(v,Av,A^2v,...,A^nv)$ is linearly dependent, $v \in \mathbb{F^n}$ and $A_{n \times n}$?
69542
Why do the $n \times n$ non-singular matrices form an "open" set?
52928
If $\mathrm{Tr}(A)=0$ then $T=R^{-1}AR$ has all entries on its main diagonal equal to $0$
62192
Proof $L{\rm{[}}\frac{{x(t)}}{t}{\rm{] = }}\int_s^\infty {X(u)du} $
2109
Max dimension of a subspace of singular $n\times n$ matrices
156727
A step in the proof of Characterization of $W^{1,\infty}$
95266
Show $|t|\leq \pi \Rightarrow |e^{it}-1|\geq 2|t|/ \pi$