### Abstract

We consider the existence of positive ω-periodic solutions for the periodic equation x^{′} (t) = a (t) e^{x (t)} x (t) - λ b (t) f (x (t - τ (t))), where a, b ∈ C (R, [0, ∞)) are ω-periodic, ∫_{0}^{ω} a (t) d t > 0, ∫_{0}^{ω} b (t) d t > 0, f ∈ C ([0, ∞), [0, ∞)), and f (u) > 0 for u > 0, τ (t) is a continuous ω-periodic function.

Original language | English (US) |
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Pages (from-to) | 581-584 |

Number of pages | 4 |

Journal | Applied Mathematics Letters |

Volume | 23 |

Issue number | 5 |

DOIs | |

State | Published - May 1 2010 |

### Keywords

- Existence
- Fixed index theorem
- Positive periodic solution

### ASJC Scopus subject areas

- Applied Mathematics

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## Cite this

Jin, Z. L., & Wang, H. (2010). A note on positive periodic solutions of delayed differential equations.

*Applied Mathematics Letters*,*23*(5), 581-584. https://doi.org/10.1016/j.aml.2010.01.015