# Solve a calculus problem?

GROUPS:
 Consider the following code: \$Assumptions = Element[f, Reals] && Element[\[Beta], Reals] && Element[\[Alpha], Reals] && Element[n, Reals] && Element[\[Epsilon], Reals] && \[Alpha] > 0 && \[Beta] > 0 && \[Mu] > 0 && \[Epsilon] > 0 && f > 0 && n > 0 f := 1 - Exp[-\[Beta] (1 - Exp[-\[Alpha]\[Epsilon]])^n] DSolve[f''[\[Epsilon]] == 0, f[\[Epsilon]], \[Epsilon]] I get the following error message : DSolve::ivar: 1-E^(-(1-Power[<<2>>])^n \[Beta]) is not a valid variable. What is my mistake? What is the correct method?
 Daniel Lichtblau 1 Vote You gave f a value so it cannot be a dependent variable (the message pretty much states this). Maybe try Clear[f] before running the DSolve.