Preface

Formal Definition: Integration is an important concept in mathematics and, together with differentiation, is one of the two main operations in calculus. Given a function ƒ of a real variable x and an interval [a, b] of the real line, the definite integral is defined informally to be the net signed area of the region in the xy-plane bounded by the graph of ƒ, the x-axis, and the vertical lines x = a and x = b.

${\displaystyle \int _{a}^{b}\!f(x)\,dx\,}$

Translation: Its all about finding the equation of higher level graphs and the areas of lower level ones - fast.