Definite integral
A definite integral assigns numbers to functions in a way that can describe displacement, area, volume, and other concepts that arise by combining infinitesimal data.
Explanation
Integration is one of the two main operations of calculus, with its inverse, differentiation. Even for the integration of elementary functions, there exists no simple or general method. Integration requires calculated guesses.
Example 1
In the drawing you see the definite integral S = ∫dx (f (x), a, b)
Example 2
You can see that , because