Complex Numbers And Quadratic Equations question 804
Question: The number of roots of the equation $ \log (-2x) $ $ =2\log (x+1) $ are [AMU 2001]
Options:
A) 3
B) 2
C) 1
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
Given, $ \log (-2x)=2\log (x+1) $
$ \Rightarrow -2x={{(x+1)}^{2}} $
$ \Rightarrow x^{2}+4x+1=0 $
Þ $ x=\frac{-4\pm \sqrt{16-4}}{2} $
Þ $ x=\frac{-4\pm \sqrt{12}}{2} $
Þ $ x=-2\pm \sqrt{3} $
Þ $ x=(-2+\sqrt{3}),(-2-\sqrt{3}) $ .
BETA
