Today in math we learned about imaginary numbers, specifically i. i is the square root of negative one. You can apply i to lasers, cell phones and more. To simplify an unsolvable square root like √-9, you can turn the answer to √9 times √-1, or 3i.
The paper given out in class with these types of problems on it is due tomorrow, I believe.
You can ask questions in the comments below! (: