## Abstract

We study the existence and uniqueness of positive solutions of the nonlinear fractional differential equation

where \(1<\alpha \le 2\). In the process we convert the given fractional differential equation into an equivalent integral equation. Then we construct appropriate mapping and employ Schauder fixed point theorem and the method of upper and lower solutions to show the existence of a positive solution of this equation. We also use the Banach fixed point theorem to show the existence of a unique positive solution. The results obtained here extend the work of Matar (AMUC 84(1):51–57, 2015 [7]). Finally, an example is given to illustrate our results.

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## Acknowledgements

The authors gratefully acknowledge the reviewers for their helpful comments.

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Boulares, H., Ardjouni, A. & Laskri, Y. Positive solutions for nonlinear fractional differential equations.
*Positivity* **21, **1201–1212 (2017). https://doi.org/10.1007/s11117-016-0461-x

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DOI: https://doi.org/10.1007/s11117-016-0461-x

### Keywords

- Fractional differential equations
- Positive solutions
- Upper and lower solutions
- Existence
- Uniqueness
- Fixed point theorems

### Mathematics Subject Classification

- Primary 26A33
- Secondary 34A12
- 34G20