test

$$ frac $$

$$
begin{eqnarray}
nablacdotvec{E} &=& frac{rho}{epsilon_0}
nablacdotvec{B} &=& 0
nablatimesvec{E} &=& -frac{partial B}{partial t}
nablatimesvec{B} &=& mu_0left(vec{J}+epsilon_0frac{partial E}{partial t} right)
end{eqnarray}
$$