MCQ
The equation ${\log _e}x + {\log _e}(1 + x) = 0$ can be written as
  • A
    ${x^2} + x - e = 0$
  • ${x^2} + x - 1 = 0$
  • C
    ${x^2} + x + 1 = 0$
  • D
    ${x^2} + xe - e = 0$

Answer

Correct option: B.
${x^2} + x - 1 = 0$
b
(b) ${\log _e}x + {\log _e}(1 + x) = 0$ $⇒$  ${\log _e}(1 + x) = {\log _e}\left( {\frac{1}{x}} \right)$

$⇒$  $x(x + 1) = 1\,\, \Rightarrow \,\,{x^2} + x - 1 = 0$

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