what is meant by  ?tell all possible equalities &inequalities involving it

The symbol , called "infinity", denotes an unbounded limit,. means that x grows beyond any assigned value, and means x is eventually less than any assigned value...

 

means that f(t) does not bound a finite area from a to b ....

 

In laymen's language, infinity is just something very large..its not defined...

It will become more clear when you learn limits and continuity....

And here are a few equalities that i remember now...

 

 

If you want to do some extra reading refer this link http://en.wikipedia.org/wiki/Infinity.