How do you do interval notation?
x∈(a,b)⟹a<x<bx∈(a,b]⟹a<x≤bx∈[a,b)⟹a≤x<bx∈[a,b]⟹a≤x≤b
∪ means or∩ means and
arnt those things union and intersection?
Yes. Glad you know these.
The union of few intervals means that x satisfies any of them, so it means "or".
The intersection of few intervals means that x must satisfy all of them, so it means "and".
:O that is a mouthful
+9675 
