Question

Can someone explain why the square root of -4 equals "2i"? what is i?

Answer 1

"i" is an imaginary unit that when squared is equal to -1. (as there is no real value that this would be possible, thus the creation of the imaginary unit i)

So the square root of -4, √-4=±2i

Answer 2

i means that it's an imaginary number, because in finding square roots technically you cant have negative numbers. so instead of saying -2 you say 2i

hope that helps!