Can anyone help me with differential calculus?

Question

1. If f(x) = 4a, how can i show that f(x+2) / f(x-1) = f(3)
2. What is the equivalent functional definition of f(x) = |x| + x ?
3. If f(x) = x – 2 / x2 + 1,what is
a. f(2a)
b. f(1/x)

Answer 1

a function x is defined as an equation with variable on the left as x only with or with out a constant
f(x) = 4a . . . is not a f(x) . . . .
in f(x+2) . . . you can not even substitute (x+2) because the there is no variable x as given
problem 2 and 3 are OK

Answer 2

1 is nonsense unless a = 1/4.

For 2, they probably mean some reference to the true fact that f(x) = 2x if x>=0 and 0 if x<=0.