Question

-√-625 ?
The possible answers are
-25i
8i√5
25i
-8i√5

Answer 1

Question for you: What is the square root of -1?
Another question: What is the square root of 625?

Answer 2

\(\LARGE\color{blue}{Hint:~~~~~~~~ \bf 625=(±25)^{2} }\)

So when it is -625, the only difference in the root is going to be the "i"

you know what I mean....go for it.