Solving function analytic expression by equation method Given that f (x) satisfies 2F (x) + F (1 / x) = 3x, find f (x) I don't understand why f (x) = 3 / x-2f (1 / x),

Solving function analytic expression by equation method Given that f (x) satisfies 2F (x) + F (1 / x) = 3x, find f (x) I don't understand why f (x) = 3 / x-2f (1 / x),

Because 2F (x) + F (1 / x) = 3x, that is, f (1 / x) = 3x-2f (x),
So f (x) = 3 / x-2f (1 / x),
After finishing f (x) = 3 / x-2f (1 / x), f (1 / x) = [3 / x-f (x)] / 2 is obtained,
If f (1 / x) = [3 / x-f (x)] / 2 is substituted into 2F (x) + F (1 / x) = 3x, 2f (x) + [3 / x-f (x)] / 2 = 3x,
The solution is f (x) = 2x-1 / X