 Hello and welcome to the session, let us understand the following question which says, let f be a function defined on closed interval a, b such that f dash x is greater than 0 for all x belongs to closed interval a, b. Then prove that function on open interval a, b. Seed on to the solution. Let x1, x2 belongs to open interval a, b such that differentiable on a, b. It is given that f dash x is greater than 0 that is differentiable on a.