Your friends are not correct in their solution. The square root of -9 is not 3 because 3 squared (3 3) equals 9, not -9. To find the square root of a negative number like -9, you need to use imaginary numbers. In mathematics, the imaginary unit \(i\) is used to represent the square root of -1. So, to find the square root of -9, you recognize that you need to handle the negative part separately. The square root of 9 is 3, and the square root of -1 is \(i\). Therefore, the square root of -9 is expressed as \(3i\), not 3