Differentiate these functions
What do you get? What does this mean?
Say you want to integrate . Writing means to say that the function satisfies . But is it the only one that satisfies this relation? Clearly, satisfies; so do and . In fact, for any number , it's true that satisfies the relation. Finding means finding the set of all function which satisfy F'(x) = f(x), i.e the set of all anti-derivatives of f(x).