Complex Numbers And Quadratic Equations question 748

Question: The equation $ {\log_{e}}x+{\log_{e}}(1+x)=0 $ can be written as [Kurukshetra CEE 1998; MP PET 1989]

Options:

A) $ x^{2}+x-e=0 $

B) $ x^{2}+x-1=0 $

C) $ x^{2}+x+1=0 $

D) $ x^{2}+xe-e=0 $

Show Answer

Answer:

Correct Answer: B

Solution:

$ {\log_{e}}x+{\log_{e}}(1+x)=0 $ Þ $ {\log_{e}}(1+x)={\log_{e}}( \frac{1}{x} ) $
Þ $ x(x+1)=1\Rightarrow x^{2}+x-1=0 $