Abstract
The aim of the current manuscript is to study a coupled system of nabla fractional equations with general summation boundary conditions depending on parameters. We deduce the expression of the Green’s function and we obtain useful bounds of it. Using these bounds, under suitable conditions, we obtain existence results by implying a few classical fixed point theorems. Then, we show that there exists an interval for the parameters, where the Green’s function is strictly positive, and we are able to deduce existence, nonexistence, and multiplicity results for our studied problem using the same theory. At the end of this work, we deliver some numerical examples to clarify our theoretical results.