Question

A certain function f has the property that f(x+y)=
f(x)+f(y) for all values of x and y. Which of the
following statements must be true when a=b?
I. f(a+b)=2f(a).
II. f(a+b)=[f(a] to the power of 2.
III. f(b) +f(b)=f(2a)

Answer 1

1 and 3 should be right