# Integrate d/dx(x^2)

 Math Emeritus Sci Advisor Thanks PF Gold P: 39,338 What in the world do you mean? If you start with a function f(x), differentiate it, then integrate that, whether you get the original function, that function plus an unknown constant, or that function plus a specific number depends on exactly what type of "integral" you are doing: $\int f(x)dx$, the indefinite integral should have an unknown constant added because it means ALL functions whose derivative is f(x) but $\int_a^xf(t)dt$ would not and the value will depend upon the choice of a.