Let the two functions be f(x) and g(x).
Create the sum or composite of the functions as
h(x) = f(x) + g(x).
In order to have inverses, both f(x) and g(x) should pass the vertical line test
Therefore the sum (or difference) of the two functions, h(x), will also pass the vertical line test.
Answer:
Because h(x) passes the vertical line test, it follows that the inverse of the composite function made by the original functions is also a function.
