The difference in the values of the integral of a function, f(x) between the two assigned values of an independent variable, x say ‘a’ ‘b’ is called the definite integral f(x) over the interval (a, b). The process employed to find such a definite integral is called definite integration. This is obtained by the following model:
∫abƒ(x)dx = g(b) – g (a)
In the above model, a and b are the lower and upper limits of integration respectively, g(a) and g(b) are the lower and upper values of integration respectively, and ∫abƒ(x)dx is the definite integral of f(x) integrated from x = a to x = b.
It may be noted that the arbitrary constant C, which is invariably attached to the model of an indefinite integral, disappears here in as much as this integral has no arbitrariness.