∫[a, b] f(x)dx represents the area surrounded by curve f(x), straight line x=a, straight line x=b and straight line y=0.

Let f(x) be the original function of F(x), then ∫[a, b] f(x)dx = F(b)-F(a).

So, to ask for definite integral, just ask for indefinite integral, and then subtract it from the function value.

Integration is the inverse operation of differentiation, that is, knowing the derivative function of a function and finding the original function in reverse. In application, the function of integration is not only this, but also widely used in summation, that is, to find the area of curved triangle. This ingenious solution is determined by the special properties of integral. Mainly divided into definite integral, indefinite integral and other integral. The properties of integral mainly include linearity, sign preservation, maximum and minimum, absolute continuity, absolute value integral and so on.

There are several definite integral formulas.

References:

Baidu Encyclopedia-Integral Formula