For your purposes, it is probably most effective to just graph the function and notice what happens as you approach the point x=3 from the left and right sides.
By the way, is perfectly valid. It's not an indeterminate form. However, it *is* a borderline case. i.e., if you went any smaller than 0, then a problem arises. This is definitely related to the problem.
For part a)
You are asked to determine
.
As said in a previous post, you should probably just graph the function and see what happens as from the left...
For part b)
Note that this function is only defined for
.
How can you make approach from the right if the function is not defined for any values of to the right of ?
c) Limits only exist when the left hand limit and right hand limit are equal.
Since there is a left hand limit but NOT a right hand limit, what does that tell you about the limit of this function?