Which condition ensures a system Ax=bAx=bAx=b has exactly one solution?
rank(A)=rank(A∣b)=nrank(A) = rank(A|b) = nrank(A)=rank(A∣b)=n (number of variables)
rank(A)<rank(A∣b)rank(A) < rank(A|b)rank(A)<rank(A∣b)
rank(A)<nrank(A) < nrank(A)<n
det(A)=0det(A) = 0det(A)=0