Exercise PhysicsWiki

$$a=b$$

$\nabla \cdot {\overrightarrow {B}}=0$ (posted by TerriC, Group 2)

$e^{i\theta }=cos(\theta )+isin(\theta )$ (Zach McDargh)

$f\lambda =c$

$r={\frac {p}{1+\varepsilon \cdot \cos \theta }}$ (posted by KimberlyWynne 19:05, 29 August 2009 (EDT))

$x={\frac {-b\pm {\sqrt {b^{2}-4ac}}}{2a}}$ (Sandy Simmons)

$e^{i\pi }+1=0$ (Steve Honeywell)

$f=\langle P,Q,R\rangle$

$\nabla f={\partial f \over \partial x}P+{\partial f \over \partial y}Q+{\partial f \over \partial z}R$ (Andrew Wray)