Indefinite integral is the operation, inverse to the differentiation. So, the task of indefinite integration defined very simple: given the function , find function F(x) such as:
F'(x) = f(x) (1)
Note, that relation (1) will not change, if one adds to the function F(x) some arbitrary constant:
(F(x) + Const)' = F'(x) + (Const)' = F'(x) + 0 = f(x),
because its derivative equals to zero. Hence, indefinite integral is defined to arbitrary constant.
Indefinite integral of the given function f(x) is called set of all its antiderivatives.
In the equation:
∫
- indefinite integral symbol,
f(x)
- integrand (subintegral function),
dx
- differential,
F(x)
- antiderivative (for function
f(x)),
Const
- arbitrary constant.
To get primitives table one need to read the derivatives table from right to left. For instance, it is known that:
(sin(x))'= cos(x)
then:
∫ cos(x) dx=sin(x)+Const