Abstract:

Determination of characteristic exponent of two dimensional linear differential equations is typically very complicated. In this paper, we establish some conclusions on the sign of characteristic exponent directly in terms of the coefficient. 

Key words: Ｐｅｒｉｏｄｉｃｃｏｅｆｆｉｃｉｅｎｔ, Ｔｗｏｄｉｍｅｎｓｉｏｎａｌ, Ｌｉｎｅａｒｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓ, Ｃｈａｒａｃｔｅｒｉｓｔｉｃｅｘｐｏｎｅｎｔ．