If Rank of n X n matrix is r, then number of non zero eigen values ?? In either of cases det(A) = 0 or if det(A) not equal 0
See here
https://math.stackexchange.com/questions/2340541/relation-between-rank-and-number-of-distinct-eigen-values
@kumar.dilip
Can you explain it in simple words..or some simple reference for it