d. \( \sqrt{9 \cdot 9 \cdot 9} \)

Did you know that the expression \( \sqrt{9 \cdot 9 \cdot 9} \) can be simplified? You can break it down into \( \sqrt{9^3} \) which is equal to \( 9^{3/2} \). This simplifies further to \( 9 \cdot \sqrt{9} \) since \( 3/2 \) means 1 whole and 1/2 leftover. That means the answer is \( 9 \cdot 3 = 27 \)! You might also find it interesting that this expression is a great way to practice the properties of exponents and roots! When dealing with roots, remember to always simplify inside the square root first, and then tackle the calculations step by step. Avoid common mistakes like trying to multiply everything inside the radical without simplifying!