The increasing function f (x) defined on R + satisfies that f (x / y) = f (x) - f (y) holds for any x, y ∈ R + 1. Find f (1) (solved) the answer is 0 2. F (4) = 1, solving inequality: F (x + 6) - f (1 / x)

The increasing function f (x) defined on R + satisfies that f (x / y) = f (x) - f (y) holds for any x, y ∈ R + 1. Find f (1) (solved) the answer is 0 2. F (4) = 1, solving inequality: F (x + 6) - f (1 / x)

f(x+6)-f(1/x)< 2= f(4)+f(4)
So: F [(x + 6) / (1 / x)] < f (4) + F (4)
Or: F [x * (x + 6)] - f (4) < f (4)
That is: F [x * (x + 6) / 4] < f (4)
F (x) is an increasing function
x*(x+6)/4< 4
The results are as follows
x^2+6x-16