You can
put this solution on YOUR website! 
is

Hence,the numberator and the denominator are of different sign.
But

for all real x.
The denomiator

must be negative and the nmerator

cannot be 0.
So,

implies
We obtain the solution set
In the interval notaion: (-oo,-2) U (-2,-1).
The above is the shortest way to solve this kind of questions.
Try to think about it. [In fact, I can get the answer by direct view
in a second. ]
If you really want to consider cases
Look the sign of the given

on the intervals
(-oo,-2),(-2,-1), (-1,+oo). You will see.
-----------*-----*----------------------
-oo -2 -1 +oo
Kenny