Recent content by katyyara

Hi I had the same question and with your clear explanation I was able to somehow solve it. My question is that to prove ker(A)=ker(AT A) can we set A as say, a 2 by 3 matrix and show iff ( A\hat{x} = \hat{0} \Longleftrightarrow (A^TA)\hat{x} = \hat{0})? Seems tedious but I did it. The...

Hi, Does anyone know how to prove rank(A)=rank(AT A) where A is any matrix and AT is the transposed of matrix A? I have difficulty to prove the part that nulity(A)=nulity(AT A). Any help will be appreciated.