All I've done is extended the idea of the definition of absolute value, which is
But, the deal is that we've got to know at what point to define our new peice. In your case, we had to solve that inequality to determine we're the stuff inside the absolute value sign would become negative. More precisely, when would be less than or equal to . As it turns out, from solving the inequality, we find that this is true when
Did I answer you question?