The inequality notation with bracket
[ ] when we want to include the end value
( ) when we don't want to include the end value
Interval (5, 100] means that 5 and 100 are the end values, we don't want to include the '5' but we want to include '100'
The inequality signs for not including end value is < and >
The inequality signs for including end value ≤ and ≥
(5, 100] = 5 < x ≤ 100
