1. The problem statement, all variables and given/known data A=[0 -9; 1 -6] Can this matrix be diagonalized? 2. Relevant equations det(A-[itex]\lambda[/itex]I)=0 3. The attempt at a solution det(A-[itex]\lambda[/itex]I)=0 gives the eigenvalues of the matrix and yields two eigenvalues that are equal, [itex]\lambda[/itex]= -3 A matrix with repeating eigenvalues are defective and can therefore NOT be diagonalized. I would further say that rank(A)=1 and nullity(A)=n-rank(A)=2-1=1.... Matlab does not agree with me.... what is wrong with my reasoning here?