In differentiation, we know that f^{\prime}(x) shows the rate of change of f(x). Therefore, by utilising integration, we can recover the original function from its rate of change function.

Essentially, from the concept of antiderivatives we have\int f^{\prime}(x) d x=f(x)+c.

Since f^{\prime}(x) represents rates of changes, thus integrating rates of changes basically gives the total change of a variable.

We have already seen this in 11.2 Average Value, Straight Line Motion, where we integrate the velocity (which is represents the rate of change of displacement) to find the total change in displacement.