Basic Circuit Analysis - mutual induc

 P: 835 Basic Circuit Analysis - mutual induc Why would the mutual inductance term be 2j? Isn't M defined by as $j1\omega$ ? If I use 2j I get the book's answer, but I don't understand why I should use 2j.
 P: 835 Oh sorry about the latex confusion. Yes, the question explicitly said that $M = j1\Omega$ I typed a small omega instead of a big one.