New posts in Functional Equations

All solutions of $f(x)f(-x)=1$

Find all polynomials satisfying $p(x)p(-x)=p(x^2)$

How to solve this Functional Equation: $f(x+1) - f(x) = e^{ax}$?

Functions $f: \mathbb{Z}^{+}\to \mathbb{R}$ satisfying $x f(y) + y f(x) = (x+y) f(x^2+y^2)$

Solving and interpreting $f(x+y)=f(x)+f(y)+x^2y$ for all $x,y \in \mathbb{R} $.

Functional equation with the property $P(x+1)=P(x)+2x+1$

Functional logarithmic equation

If $f : \mathbb R \rightarrow \mathbb R $ such that $f(x^2+x)+2f(x^2-3x+2) = 9x^2-15x$. Find $f(2016)$.

A possible solution to $\sqrt {5-x}=5-x^2$ (without taking square from both sides)

Find the function $f(x)$ if $f(x+y)=f(x-y)+2f(y)+xy$