To simplify \( 56 \sqrt{7} \), first note that \( \sqrt{7} \) is already in its simplest form.
You can calculate it as follows:
- \( 56 \) can be factored as \( 8 \times 7 \).
- Therefore, \( 56 \sqrt{7} = 8 \cdot 7 \cdot \sqrt{7} = 8 \sqrt{49} = 8 \cdot 7 = 392 \).
Thus, \( 56 \sqrt{7} \) simplifies to \( 392 \).
The correct response is 392.