MathDB
Uncountably much solutions

Source: IMC 2002 day 1 problem 5

October 7, 2005
functionreal analysisreal analysis solved

Problem Statement

Prove or disprove the following statements: (a) There exists a monotone function f:[0,1][0,1]f : [0, 1] \rightarrow [0, 1] such that for each y[0,1]y \in [0, 1] the equation f(x)=yf(x) = y has uncountably many solutions xx. (b) There exists a continuously differentiable function f:[0,1][0,1]f : [0, 1] \rightarrow [0, 1] such that for each y[0,1]y \in [0, 1] the equation f(x)=yf(x) = y has uncountably many solutions xx.