Prove that if A is upper triangular and B is the matrix

[DavidLiew]

How to prove that if A is upper triangular and B is the matrix that results when the ith row and jth column of A are deleted, then B is upper triangular if i<j.

 

[Bacle]

It seems like induction could work here. Have you tried it.? . Try showing it

works for small values of n, say , 2,3,4 , and see how to generalize for the

inductive step.