MathDB
Problem 8 IMC 2004 Macedonia

Source:

July 26, 2004
functionintegrationgeometryperimeterinequalitiesIMCcollege contests

Problem Statement

Let f,g:[a,b][0,)f,g:[a,b]\to [0,\infty) be two continuous and non-decreasing functions such that each x[a,b]x\in [a,b] we have axf(t) dtaxg(t) dt  and abf(t) dt=abg(t) dt. \int^x_a \sqrt { f(t) }\ dt \leq \int^x_a \sqrt { g(t) }\ dt \ \ \textrm{and}\ \int^b_a \sqrt {f(t)}\ dt = \int^b_a \sqrt { g(t)}\ dt. Prove that ab1+f(t) dtab1+g(t) dt. \int^b_a \sqrt { 1+ f(t) }\ dt \geq \int^b_a \sqrt { 1 + g(t) }\ dt.