Which condition is equivalent to saying a n×nn \times nn×n matrix AAA is invertible?
det(A)=0\det(A) = 0det(A)=0
det(A)≠0\det(A) \neq 0det(A)=0
det(A)=1\det(A) = 1det(A)=1
A=ATA = A^TA=AT