How boundary conditions help in finding integration constant

1. Oct 11, 2015

gracy

How to find value of integration constant?I know with the help of boundary conditions,but How boundary conditions help in finding integration constant?

2. Oct 11, 2015

blue_leaf77

An integral $I$ without integration limits is an indefinite integral
$$I(x) = \int f(x) dx = F(x) + C$$
If you know at least one boundary condition, e.g. $I(x)$ at $x=a$, you can plug in these values to get
$$I(a) = F(a) + C$$
which can be solved for C.