If I interpret your question correctly the limit you have to calculate is:
Have you ever seen that:
(a>0 gives , a<0 gives )
?
i am not sure if i am posting in the right section anyway i have a problem that is driving me insane, basically i have solve a limit for -4 while the expression is -(9/x+4).
If i input -4 it will give me -9/0 which is wrong. The tip is that i need to do some algebraical modification to the expression, but i tried everything and it always gives me undefined. I appreciate your time...
Thank you