When $a \ne 0$, there are two solutions to $(ax^2 + bx + c = 0)$ and they are $$ x = {-b \pm \sqrt{b^2-4ac} \over 2a} $$

Maxwell's equations:

equation	description
$\nabla \cdot \vec{\mathbf{B}} = 0$	divergence of $\vec{\mathbf{B}}$ is zero
$\nabla \times \vec{\mathbf{E}}, +, \frac1c, \frac{\partial\vec{\mathbf{B}}}{\partial t} = \vec{\mathbf{0}}$	curl of $\vec{\mathbf{E}}$ is proportional to the rate of change of $\vec{\mathbf{B}}$
$\nabla \times \vec{\mathbf{B}} -, \frac1c, \frac{\partial\vec{\mathbf{E}}}{\partial t} = \frac{4\pi}{c}\vec{\mathbf{j}} \nabla \cdot \vec{\mathbf{E}} = 4 \pi \rho$	wha?