Question

Which of the following are quadratic equation in x? 

`(x+1/x)^2=2(x+1/x)+3` 

Answer 1

`(x+1/x)^2=-2(x+1/x)+3` 

⇒`((x^2+1)/x)^2=2((x^2+1)/x)+3` 

⇒`(x^2+1)^2=2x(x^2+1)+3x^2` 

⇒` x^4+2x^2+1=2x^3+2x+3x^2` 

⇒`x^4-2x^3-x^2-2x+1=0` 

This is not of the form `ax^2-bx+c=0` 

Hence, the given equation is not a quadratic equation.