Good evening,

i have an assignment for tomorrow and i still have 2 exercises that i didn't know how to resolve them.

I will be more than grateful if someone could help me.

#1

Let A be an nxn invertible matrix. Show that if A is in upper (lower) triangular form,then A-1 is also in upper(lower) triangular form

#2

Suppose B is row equivalent to the nxn invertible matrix A.Show that B is invertible.

Thanks in advanced!