The expression in the image is $\sqrt{-24}$.

This is an example of a square root of a negative number, which involves complex numbers. The square root of a negative number can be rewritten using the imaginary unit $i$, where $i = \sqrt{-1}$.

We can express this as: $\sqrt{-24} = \sqrt{-1 \times 24} = \sqrt{-1} \times \sqrt{24} = i \times \sqrt{24}$ Now, simplifying $\sqrt{24}$: $\sqrt{24} = \sqrt{4 \times 6} = \sqrt{4} \times \sqrt{6} = 2\sqrt{6}$ Thus, the final simplified form is: $\sqrt{-24} = 2i\sqrt{6}$

Would you like further details or have any other questions?

Here are five related questions:

1. How do you simplify square roots of negative numbers generally?
2. What is the significance of the imaginary unit $i$ in complex numbers?
3. How do you simplify radicals like $\sqrt{24}$?
4. What are some applications of complex numbers in physics or engineering?
5. How do you add or subtract complex numbers?

Tip: When simplifying square roots of negative numbers, always factor out $\sqrt{-1}$ as $i$ first.