1. The problem is to simplify the expression $-\sqrt{-48}$. 2. Recall that the square root of a negative number involves imaginary numbers: $\sqrt{-a} = i\sqrt{a}$ where $a > 0$. 3. Apply this to $\sqrt{-48}$: $$\sqrt{-48} = i\sqrt{48}$$ 4. Simplify $\sqrt{48}$ by factoring: $$\sqrt{48} = \sqrt{16 \times 3} = \sqrt{16} \times \sqrt{3} = 4\sqrt{3}$$ 5. Substitute back: $$\sqrt{-48} = i \times 4\sqrt{3} = 4i\sqrt{3}$$ 6. Now apply the negative sign outside the square root: $$-\sqrt{-48} = -4i\sqrt{3}$$ 7. Final simplified form is: $$\boxed{-4i\sqrt{3}}$$