That's cheating. One would need to also define F, c, ε0, J, assuming ∇ is known from calculus. Which would make for 5 lines :)
You can't really get away with just knowing del from vector calculus, as this is the geometric-calculus del.
∇F = ∇ . F + ∇ /\ F
But for defining the terms you're going to need a couple paragraphs to go along with the one equation.
For those curious, ∇ . F is called 'interior derivative' and relates to divergence, whereas ∇ /\ F is called 'exterior derivative' and relates to curl.
Well, but if you need to define the gradient, curl and divergence and every term in the equations, the typical representation would be more than 20 lines. So I think that it's a fair comparison.