ABSTRACT
The notion of integration was developed much earlier than differentiation. The main idea of integration is to assign a real number A, called the “area”, to the region R (Figure 6.1) bounded by the curves x = a, x = b, y = 0, and y = f(x), where we assume that f is non-negative. The number, A, the area of the region
R, is called the integral of f over [a, b] and denoted by the symbol ∫ b a f(x) dx.
