We refer to and as differentials.


Use differentials to approximate .

That is, when decreases by 3, decreases by approximately . Thus,

Multivariate Differentials

Same thing, but use

Physics Stuff

Differential Length Element

we want to make a small differential length (let us call it ) in an arbitrary direction then we will take a small step in direction, a small step in direction and a small step in direction. Thus, a differential length element will be

Differential Elements

To define arbitrary shapes, we use differential elements.

Thus, there are three differential elements in length i.e. , , and . is a small step we take in the 𝑥̂ direction, is a small step we take in the 𝑦̂ direction and dz is a small step we take in 𝑧̂ direction

Differential surface elements () are very-very small surfaces defined by two differential elements)