Question 5792
 T is diagonalizable iff the set of all eigenvectors can generate the whole
 vector space. (That is : try to find a basis consisting of eigenvectors)

 I cannot tell you more, since it seems that you did not ask this
 high level question seriously and posted your question in
 a very sloppy way.

 Moreover, you insult your own question with other baby level problems
 [Where nobody understanding linear algebra.]

 Kenny