The analytic expression of F (x) by function f (2x) = 4x + 1

The analytic expression of F (x) by function f (2x) = 4x + 1

Let 2x = t, then x = t / 2, and substitute f (T) = 4 * t / 2 + 1 = 2T + 1,
So f (x) = 2x + 1