That would depend on what the question or problem is. There are many, many problems for which -3.5 is the solution. There are even more problems for which -3.5 is not the solution, though.
This question isn't well stated. -3.5 is a solution to the equation 2x + 7 =0, as well as
many others, but it is not a solution to many other equations. Please specify what problem is being solved.
