What does 5i mean

In terms of imaginary and/or complex numbers, 5i means 5 times the square root of negative one.

 

\(5i = 5\sqrt{-1}\)

 

Although it could be a variable in physics, especially with certain coordinate systems.

 

If you could specify the context of " 5i ", we could help you more, but I hope this was helpful!

 

-LambLamb