Complex Numbers And Quadratic Equations question 749

Question: If $ x=\sqrt{6+\sqrt{6+\sqrt{6+….to\infty }},} $ then [Pb. CET 1999]

Options:

A) x is an irrational number

B) $ 2<x<3 $

C) $ x=3 $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

$ x=\sqrt{6+x} $ , $ x>0\Rightarrow x^{2}=6+x,x>0 $
$ \Rightarrow x^{2}-x-6=0,x>0 $
$ \Rightarrow x=3,x>0 $ .