Find the domain and the range of each of the following real function:
$f(x)=\frac{1}{x}$
Given: $f(x)=\frac{1}{x}$
Need to find: Where the functions are defined.
Let, $f(x)=\frac{1}{x}=y$ ........(1)
To find the domain of the function f(x) we need to equate the denominator of the function to 0.
Therefore,
$x=0$
It means that the denominator is zero when $\mathrm{x}=0$
So, the domain of the function is the set of all the real numbers except 0 .
The domain of the function, $\mathrm{D} \mathrm{f}(\mathrm{x})=(-\infty, 0) \cup(0, \infty)$.
Now, to find the range of the function we need to interchange $x$ and $y$ in the equation no. (1)
So the equation becomes,
$\frac{1}{y}=x$
$\Rightarrow y=\frac{1}{x}=f\left(x_{1}\right)$
To find the range of the function $\mathrm{f}\left(\mathrm{x}_{1}\right)$ we need to equate the denominator of the function to 0 .
Therefore
$x=0$
It means that the denominator is zero when $x=0$
So, the range of the function is the set of all the real numbers except 0 .
The range of the function, $R_{f(x)}=(-\infty, 0) \cup(0, \infty)$.