- Thread starter
- #1
Hi Casio,If an example was written;
h(x) = 1/x and the function h has domain R excluding 0, could somebody please explain how the two open intervals include (- infinity, 0) and (0, infinity)?
![]()
Very much appreciated for the help and effort you have put into this thread. May I expand and ask additonal questions in relation to what you have wrote above please.In general interval notation, "[" or "]" mean "include this endpoint" while "(" and ")" mean "do not include this endpoint".
[a, b] means "all numbers between a and b and a and b themselves".
In set notation: [tex][a, b]= \{ x| a\le x\le b\}[/tex]
(a, b) means "all numbers between a and b not including a and b".
In set notation: [tex](a, b)= \{ x| a< x< b\}[/tex]
[a, b) means "all numbers between a and b including a but not b".
In set notation: [tex][a, b]= \{ x| a\le x< b\}[/tex]
(a, b] means "all numbers between a and b including b but not a".
In set notation: [tex][a, b]= \{ x| a< x\le b\}[/tex]
One always use [tex](-\infty,0][/tex] and [tex](0.\infty)[/tex] i.e. with infinity we use ( or ).The problem I can't understand at the present is in the use of infinity, whether that be positive or negative infinity and how to correctly interpret it in the use of solutions to questions?