Question

What is the domain and range of `f(x) = -x/2`?

Answer 1

`x in RR` and `f(x) in RR`
OR
`x in (-oo,+oo)` and `f(x) in (-oo,+oo)`

Explanation:

The domain is the set of all possible `x`-values which will make the function "work", and will output real `f(x)`-values.

So when we have the function `f(x)=-x/2` we can let `x` be any real number and we will always get a real and defined value of `f(x)`.
Therefore the domain is `RR`.

The range is the resulting `f(x)`-values we get after substituting all the possible `x`-values.

Here too, all the possible values of `f(x)` are all the real numbers.
Therefore the range is also `RR`.

Example -->

Let `x=sqrt2` which is a real number.
then we'd get `f(x)=-sqrt2/2` which is also a real number.