# Thread: confusing derivatives question, don't know which notation to preserve?

1. ## confusing derivatives question, don't know which notation to preserve?

I'm not sure if $\displaystyle {d}^{3}y$ is equal to $\displaystyle {(dy)}^{3}$

and if $\displaystyle {dx}^{2}$ means $\displaystyle dx . dx$

2. ## Re: confusing derivatives question, don't know which notation to preserve?

... they didn't teach you basic notation?

$\dfrac {d^2 x}{{dy}^2}$ means the 2nd deriviative

$\dfrac {d^3 x}{{dy}^3}$ means the 3rd derivative

$\dfrac {d^n x}{{dy}^n}$ means the nth derivative

if it's understood you are differentiating with respect to $x$ you can use shorthand notation

$y'=\dfrac {dy}{dx}$

$y''=\dfrac {d^2 y}{{dx}^2}$

etc.