A real valued function f is such that f ( x + y) = x  + f(f(y))

Q1. Find f (9)
a. 9
b. 3
c. 6
d. 0

Q2. Find f (a^2 + b^2)
a. (a+b)^2 – (a+b)
b. (a+b)^3 – (a+b)^2
c. [(a+b)^2]/4 – (a+b)
d. None of these