Find the maximum and minimum values, if any, of the following functions given by
(i) $f(x)=|x+2|-1$
(ii) $g(x)=-|x+1|+3$
(iii) $h(x)=\sin (2 x)+5$
(iv) $f(x)=|\sin 4 x+3|$
(v) $h(x)=x+1, x \in(-1,1)$
(i) $f(x)=|x+2|-1$
We know that $|x+2| \geq 0$ for every $x \in \mathbf{R}$.
Therefore, $f(x)=|x+2|-1 \geq-1$ for every $x \in \mathbf{R}$.
The minimum value of $f$ is attained when $|x+2|=0$.
$|x+2|=0$
$\Rightarrow x=-2$
$\therefore$ Minimum value of $f=f(-2)==|-2+2|-1=-1$
Hence, function f does not have a maximum value.
(ii) $g(x)=-|x+1|+3$
We know that $-|x+1| \leq 0$ for every $x \in \mathbf{R}$.
Therefore, $g(x)=-|x+1|+3 \leq 3$ for every $x \in \mathbf{R}$.
The maximum value of $g$ is attained when $|x+1|=0$.
$|x+1|=0$
$\Rightarrow x=-1$
$\therefore$ Maximum value of $a=a(-1)=-|-1+1|+3=3$
(iii) $h(x)=\sin 2 x+5$
We know that $-1 \leq \sin 2 x \leq 1$.
$\Rightarrow-1+5 \leq \sin 2 x+5 \leq 1+5$
$\Rightarrow 4 \leq \sin 2 x+5 \leq 6$
Hence, the maximum and minimum values of h are 6 and 4 respectively.
(iv) $f(x)=|\sin 4 x+3|$
We know that $-1 \leq \sin 4 x \leq 1$.
$\Rightarrow 2 \leq \sin 4 x+3 \leq 4$
$\Rightarrow 2 \leq|\sin 4 x+3| \leq 4$
Hence, the maximum and minimum values of f are 4 and 2 respectively.
(v) $h(x)=x+1, x \in(-1,1)$
Here, if a point $x_{0}$ is closest to $-1$, then we find $\frac{x_{0}}{2}+1>x_{0}+1$ for all $x_{0} \in(-1,1)$.
Also, if $x_{1}$ is closest to 1 , then $x_{1}+1<\frac{x_{1}+1}{2}+1$ for all $x_{1} \in(-1,1)$.
Hence, function h(x) has neither maximum nor minimum value in (−1, 1).