MCQ
The range of the function $f(x)=\frac{1+x^2}{x^2}$ is
  • A
    (0,1)
  • B
    [0, 1]
  • $(1, \infty)$
  • D
    $[1, \infty)$

Answer

Correct option: C.
$(1, \infty)$
(C)
$f (x)$ is defined for all $x \in R -\{0\}$.
So, $\operatorname{dom}(f)=R-\{0\}$
Let $y=\frac{1+x^2}{x^2}$
$\Rightarrow x= \pm \sqrt{\frac{1}{y-1}}$
For $x$ to be real, $y-1>0 \Rightarrow y \in(1, \infty)$

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