Tensor moment of inertia -- why is there a "-" sign?

Usually, there are six negative signs. Did you have a particular one in mind?

 

As it was pointed out, there are several negative signs. Which one are you talking about?

 

Are you asking what it represents or in what conditions that you use it? I don't know why it is there either, just trying to help clarify the question.

 

This question does not make a lot of sense. A better question would be: why is the moment of inertia tensor defined the way it is defined?