MathHomework graphing

Question

If f{x}=-5, what is x

Answer 1

if f(x) = -5, x could be any real number, depending on what f(x) is

if f(x) =x, then when f(x)=-5, x =-5

if f(x)= -sqrx then when f(x)=-5, x=25

and endless other functions

if f(x)=+sqrx =-5, then x has no real solution, DNE or Does Not Exist