#### Answer

$\sqrt{3} + \sqrt{13}$ (cannot be simplified further)

#### Work Step by Step

A radical involving a square is already in lowest terms when the radicand has no perfect square factor.
Note that the radicands of $\sqrt{3}$ and $\sqrt{13}$ are prime numbers, which means that they have no factors other than themselves.
Therefore, the given expression is already in lowest terms.