Suppose zero is an eigenvalue of the matrix A what does that
     Suppose zero is an eigenvalue of the matrix A. what does that tell you about the multispecies of A? Is A invertible or not? 
  
  Solution
There must be some nontrivial
 vector x for which
 Ax = 0x = 0
 which implies that A is not invertible which implies a whole lot of things given our Invertible Matrix
 Theorem.
 Invertible Matrix Theorem: The n × n matrix A is invertible if and only if 0 is not an
 eigenvalue of A

