When situations such as these arrive. I mean ones you plug in the variable and the solution yields undefined; it's always a good habit to calculate the left and right hand limits by setting up a table. If a solution is said to be undefined it is because the the numbers at a certain point on the graph are heading in two totally different directions. You can see the work for problem one by clicking the link under #1. Keep in mind you can solve any limit problem by looking at a graph or setting up a table.
I am still working on this problem. I know the answer is 0 because when you take the limit of both the left and right and side the number is limiting 0. I will keep you posted when I get the work.
Best of Luck!