Question 179817
domain is the set of input values in a function
:
range is the set of output values dependent on the domain values.
:
real life situation: lets see there are 1000's of them ....let take your phone for instance. let say you are charged $45 a month and 3 cents a minute for  every calls exceeding 500 minutes for the month.

:
so the Cost as a funtion of time would be
:
C(t)=45+.03(t-500)
:
obviously this is written so that there is no extra charge for calls at or under 500 minutes that is {{{t<=500}}}