The most general anti-derivative a function. >[!info] > For a given function $f(x)$ and an anti-derivative of the function, $F(x)$, the indefinite integral is $F(x) + C$, where $C$ is a constant. >[!example] For the function $\huge\deriv{y}{x} = \frac{1}{x^2} + x$, we know that $\huge y(2) = 4$, find $\huge y=f(x)$. >>[!check] Solution: $y = \int \pa{\frac{1}{x^2} + x}\d{x} = -\frac{1}{x} + \frac{x^2}{2} + C$