Question:
f, g and h are three functions defined from R to R as following:
(i) $f(x)=x^{2}$
(ii) $g(x)=x^{2}+1$
(iii) $h(x)=\sin x$
That, find the range of each function.
Solution:
(i) $f: R \rightarrow R$ such that $f(x)=x^{2}$
Since the value of x is squared, f(x) will always be equal or greater than 0.
$\therefore$ the range is $[0, \infty)$
(ii) $g: R \rightarrow R$ such that $g(x)=x^{2}+1$
Since, the value of $x$ is squared and also adding with $1, g(x)$ will always be equal or greater than 1 .
$\therefore$ Range of $g(x)=[1, \infty)$
(iii) $\mathrm{h}: \mathrm{R} \rightarrow \mathrm{R}$ such that $\mathrm{h}(\mathrm{x})=\sin \mathrm{x}$
We know that, $\sin (x)$ always lies between $-1$ to 1+
$\therefore$ Range of $h(x)=(-1,1)$