Q94 / 180 · COMEDK 2017 · Mathematics

$f(x)=\left(\frac{5}{x}+7\right)$, where $x \neq 0$ is decreasing for

  • A
    $x \in R$
  • Correct answer
    B
    $x \in R-\{0\}$
  • C
    $x \in R-\{1\}$
  • D
    $x \in R-\{-1,1\}$

Solution

$f(x)=\left(\frac{5}{x}+7\right)$ $\Rightarrow f^{\prime}(x)=\frac{-5}{x^{2}} < 0$ for all $x \in R$, where $x \neq 0$. Hence, $f(x)$ is decreasing for $x \in R-\{0\}$.

Hence, the correct answer is option: 'B'.

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