doubt

answer is b) 2+- root 5

the question needs little modification...

it will be infinity in place of 2 ....

so make an equation 

x= 4 + 1/x 

now make a quadratic equation and solve........

it will be infinity in place of 2

Solution,

Assum

                                                                            X=4+

                                                                          =4x+1

                                                                          4x+1=0

Now solve the equation and find x

  Assum

   X=4+

=4x+1

     4x+1=0

Now solve the equation and find x