How to solve this equation?

[polymath257]

That’s true. You don’t even know that they’re called ‘complex numbers.’

Boru

What's the difference?

The correct term is 'complex numbers', just like the correct term for fractions is 'rational numbers'.  You don't get to change to a different adjective even if it would be correct in ordinary language.

And, really, the only thing you need to know about complex numbers is that i^2 =-1. All the rest of algebra works the same (although order properties don't exist).