Answer
Let f(x) = x is one to one, and g(x) = -x is also one to one
(f+g)(x) = 0 for all x, hence f+g is not one to one.
Work Step by Step
Let f(x) = x is one to one, and g(x) = -x is also one to one
(f+g)(x) = 0 for all x, hence f+g is not one to one.