# Thread: domain of function help

1. ## domain of function help

The domain of a function f is the largest subset of R at which f can be defined. write the domain of the following function in interval notation i.e using

[,(,),] , U n , \

$f(x) = \sqrt{(x+2)}$

$f(x) = tan \pi x$

I know for the first one, in order for it to be defined in the set of reals, it cannot be negative, so i have to exclude all numbers that are going to make that function negative, but i dont know how to write this in 'interval notation'

and no idea how to go about the second one, any help appreciated

2. ## Re: domain of function help

Originally Posted by Tweety
The domain of a function f is the largest subset of R at which f can be defined. write the domain of the following function in interval notation i.e using

[,(,),] , U n , \

$f(x) = \sqrt{(x+2)}$

$f(x) = tan \pi x$

I know for the first one, in order for it to be defined in the set of reals, it cannot be negative, so i have to exclude all numbers that are going to make that function negative, but i dont know how to write this in 'interval notation'

and no idea how to go about the second one, any help appreciated
The simplist: x + 2 >= 0 ==> x >= -2

Sketch the graph of tan(pi*x) over one period and conclude the domail over one period.

3. ## Re: domain of function help

Originally Posted by Tweety
The domain of a function f is the largest subset of R at which f can be defined. write the domain of the following function in interval notation i.e using [,(,),] , U n , \
$f(x) = \sqrt{(x+2)}$
If you follow the directions then $[-2,\infty)=\mathbb{R}\setminus (-\infty,-2)$.

4. ## Re: domain of function help

thank you, i understand now