Sum of two matrices equals product; prove that the matrices commute
6096
If $A+B=AB$ then $AB=BA$
35834
Is the product of any two invertible diagonalizable matrices diagonalizable?
63879
Prove that $\sum_{k=0}^r {m \choose k} {n \choose r-k} = {m+n \choose r}$
70606
Show that the LU decomposition of matrices of the form $\left[\begin{smallmatrix}0& x\\0 & y\end{smallmatrix}\right]$ is not unique
142640
Prove determinant of a matrix $=\prod_{j<i}(a_i-a_j)$
128990
Prove that, at least one of the matrices $A+B$ and $A-B$ has to be singular
106511
Determinant of the sum of matrices: $\det (A + B^T) = \det(A^T + B)$
13026
Prove that if AB=I_m, then rk(A)=rk(B).
116798
First-year matrix problem: How do you show that a sum of an identity matrix and another matrix is equal to the sum's inverse?
19203
Is the rank of a matrix the same of its transpose? If yes, how can I prove it?
17032
If $ab=ba$, Prove $a^2$ commutes with $b^2$
87262
How to prove positive semidefiniteness of two matrices through Schur Complement?
116376
Prove the determinant is the product of its diagonal entries
38945
On the proof that the product of diagonal matrices is a diagonal matrix?
77554
Inverse of the sum of matrices
70827
Prove that $\sum_{i = n - b}^{a - m} {a - i \choose m}{b + i \choose n} = {a + b + 1 \choose m + n + 1}$
57318
Property of the conjugate transpose matrix with inner product