1. **State the problem:** Rewrite the expression $-\sqrt{-76}$ as a complex number and simplify all radicals. 2. **Recall the imaginary unit:** The imaginary unit $i$ is defined as $i = \sqrt{-1}$. 3. **Rewrite the expression using $i$:** $$-\sqrt{-76} = -\sqrt{76 \times (-1)} = -\sqrt{76} \times \sqrt{-1} = -\sqrt{76} \times i$$ 4. **Simplify the radical $\sqrt{76}$:** Since $76 = 4 \times 19$, we have $$\sqrt{76} = \sqrt{4 \times 19} = \sqrt{4} \times \sqrt{19} = 2\sqrt{19}$$ 5. **Substitute back:** $$-\sqrt{-76} = -2\sqrt{19} \times i = -2i\sqrt{19}$$ 6. **Final answer:** The expression rewritten as a complex number is $$-2i\sqrt{19}$$