MCQ
$\lim _{x \rightarrow 0}\left(\frac{3+5 x}{3-4 x}\right)^{\frac{1}{x}}=$
  • $e^3$
  • B
    $e^6$
  • C
    $e^9$
  • D
    $e ^{-3}$

Answer

Correct option: A.
$e^3$
(A)
$\lim _{x \rightarrow 0}\left(\frac{3+5 x}{3-4 x}\right)^{\frac{1}{x}}=\lim _{x \rightarrow 0}\left(\frac{1+\frac{5 x}{3}}{1-\frac{4 x}{3}}\right)^{\frac{1}{x}}$
$=\frac{\lim _{x \rightarrow 0}\left[\left(1+\frac{5 x}{3}\right)^{\frac{3}{5 x}}\right]^{\frac{5}{3}}}{\lim _{x \rightarrow 0}\left[\left(1-\frac{4 x}{3}\right)^{\frac{-3}{4 x}}\right]^{\frac{-4}{3}}}$
$=\frac{ e ^{\frac{5}{3}}}{ e ^{\frac{-4}{3}}}= e ^3$

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