I got 3 different answers and I don’t know which one is right

±2i√10

Step-by-step explanation:

since it's a negative, you have to take out the i. and then you simplify 40, which is √2 x 2 x 2 x 10

you only can take out 2, so it's 2i√10. Then you add a ± to the outside because we have 2 different answers for it.