The expression is undefined when the denominator is 0.

Factor it:

Set each = 0 to find the x-value that makes it 0.
z+1 = 0
Subtract 1 from both sides.
z=-1
z-5=0
Add 5 to both sides.
z=5
The expression is undefined when z=-1 and when z=5.
If you need help understanding math so you can solve these problems yourself, then one on one online tutoring is the answer ($30/hr). If you need faster solutions with guaranteed detailed answers, then go with personal problem solving ($3.50-$5.50 per problem). Contact me at fcabanski@hotmail.com