In this paper, we consider the Drazin inverse of a sum of two matrices and derive additive
formulas under conditions weaker than those used in some recent papers on the subject.
As a corollary we get the main results from the paper of Yang and Liu [H. Yang, X. Liu, The
Drazin inverse of the sum of two matrices and its applications, J. Comput. Appl. Math. 235
(2011) 1412–1417]. As an application we give some new representations for the Drazin
inverse of a block matrix.
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