I don't believe you're supposed to. "i" is a stand in for "the square root of -1" which, if you try to work THAT out, it gets really messy really quick. Try solving for X like a normal algebra problem and if that doesn't get you the right answer then get a calculator and find the square root of -1. Then multiply that by your answer. Different curriculums want different answers when it comes to "i" sometimes :) hope this helps you!