MathDB
Miklos Schweitzer 1963_6

Source:

September 19, 2008
functionintegrationreal analysisinequalitieslimitreal analysis unsolved

Problem Statement

Show that if f(x) f(x) is a real-valued, continuous function on the half-line 0x< 0\leq x < \infty, and 0f2(x)dx< \int_0^{\infty} f^2(x)dx <\infty then the function g(x)\equal{}f(x)\minus{}2e^{\minus{}x}\int_0^x e^tf(t)dt satisfies \int _0^{\infty}g^2(x)dx\equal{}\int_0^{\infty}f^2(x)dx. [B. Szokefalvi-Nagy]