Vectors

Technically, every vector \mathbf{r} (the r standing for “radius” from the arbitrarily chosen origin) should be written in terms of basis vectors, e.g. \mathbf{\hat{x}}, like so:

\mathbf{r}=x\mathbf{\hat{x}}+y\mathbf{\hat{y}}+z\mathbf{\hat{z}}

But in reality everybody knows about the basis vectors, and then can be assumed. You can write the same vector by omitting them — so long as you realize, conceptually, that they are implicit in the formula:

\mathbf{r}=(x,y,z)