MathDB
Function Problem

Source: 1992 National High School Mathematics League, Exam One, Problem 6

February 26, 2020
function

Problem Statement

f(x)f(x) is a function defined on R\mathbb{R}, satisfying: f(10+x)=f(10x),f(20x)=f(20+x)f(10+x)=f(10-x),f(20-x)=-f(20+x). Then, f(x)f(x) is (A)\text{(A)}even function, but not periodic function (B)\text{(B)}even function, and periodic function (C)\text{(C)}odd function, but not periodic function (D)\text{(D)}odd function, and periodic function