Functional Equation involving Golden Ratio
14975
Functions satisfying $f:\mathbb{N}\rightarrow\ \mathbb{N}$ and $f(f(n))+f(n+1)=n+2$
81055
Functional Equation simple problem
21780
Period of the sum/product of two functions
17175
Problem in solving functional equation $f(x^2 + yf(x)) = xf(x+y)$
34888
An MCQ for finding the extremal of the functional $J = \int_{a}^{b} F(x, y, y^{'})$
39090
Finding functions such that $f(g(x)) = f(x)g(x)$
53231
A slightly stronger version of the Goldbach conjecture?
104209
Functional equation - Cyclic Substitutions
29403
Finding functions $f: \Bbb R_*^+ \to \Bbb R_*^+$ with certain properties
146719
Functional equation $f(r \cos \varphi)+f(r \sin \varphi)=f(r)$
65418
Solve these functional equations: $\int_0^1\!{f(x)^2\, \mathrm{dx}}= \int_0^1\!{f(x)^3\, \mathrm{dx}}= \int_0^1\!{f(x)^4\, \mathrm{dx}}$
59105
New Golden Ratio Construction with Two Adjacent Squares and Circle. Have you seen anything similar?
34074
Nonlinear Functional Equation $f(x)^{2}=f\left(\frac x a\right)$
78033
Evaluating $\prod_{n=1}^{\infty}\left(1+\frac{1}{2^n}\right)$
120676
A certain element which makes functionals positive
144859
Finding parameters for $f(x) = x^2 + 2(m − a)x + 3am −2 = 0$ that satisfy a condition.
52858
Find $f$ if $ f(x)+f\left(\frac{1}{1-x}\right)=x $