For the function $\mathrm{f}(\mathrm{x})=x+\frac{1}{x}$
(a) $x=1$ is a point of maximum
(b) $x=-1$ is a point of minimum
(c) maximum value $>$ minimum value
(d) maximum value $<$ minimum value
(d) maximum value $<$ minimum value
Given : $f(x)=x+\frac{1}{x}$
$\Rightarrow f^{\prime}(x)=1-\frac{1}{x^{2}}$
For a local maxima or a local minima, we must have
$f^{\prime}(x)=0$
$\Rightarrow 1-\frac{1}{x^{2}}=0$
$\Rightarrow x^{2}-1=0$
$\Rightarrow x^{2}=1$
$\Rightarrow x=\pm 1$
Now,
$f^{\prime \prime}(x)=\frac{2}{x^{3}}$
$\Rightarrow f^{\prime \prime}(1)=\frac{2}{1}=2>0$
So, $x=1$ is a local minima.
Also,
$f^{\prime \prime}(-1)=-2<0$
So, $x=-1$ is a local maxima.
The local minimum value is given by
$f(1)=2$
The local maximum value is given by
$f(-1)=-2$
$\therefore$ Maximum value $<$ Minimum value