1. The last form is often used, and in fact is a shorthand for the others but be careful with it; in fact, avoid it if you can.

It can cause utter confusion if, as sometimes happens, the variable x on the left is a parameter in f. In the first or second notation this is easily handled:

2. This notation may seem strange. Get used to it.                

3. Since two different functions, for example x and x + 3, can have the same derivative, a function f can have many different antiderivatives.

Thus the antiderivative of f, like the square root, needs an extra condition to be completely defined.