MCQ
The value of $k$ for which the function $f\left( x \right) = \left\{ \begin{gathered} {\left( {\frac{4}{5}} \right)^{\frac{{\tan \,4x}}{{\tan \,5x}}}},\,\,\,\,0 < x < \frac{\pi }{2} \hfill \\  k + \frac{2}{5}\,\,\,,\,\,\,\,\,\,\,\,\,\,\,x = \frac{\pi }{2} \hfill \\ \end{gathered}  \right.$ is continuous at  $x\,= \frac{\pi}{2}$ is
  • A
    $\frac{17}{20}$
  • B
    $\frac{2}{5}$
  • $\frac{3}{5}$
  • D
    $-\frac{2}{5}$

Answer

Correct option: C.
$\frac{3}{5}$
c
$\mathop {\lim }\limits_{x \to \pi /2} f\left( x \right) = f\left( {\pi /2} \right)$

$k + 2/5 = 1$

$k = 1 - \frac{2}{5}$

$k = \frac{3}{5}$

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