Question

Which of the following is a quadratic equation? 

(a)` (x^2+1)=(2-x)^2+3`              (b)` x^3-x^2=(x-1)^3` 

(c) `2x^+3=(5+x)(2x-3)`                (d) None of these  

Answer 1

`x^3-x^2=(x-1)^3` 

∵ `x^3-x^2=(x-1)^3` 

⇒ `x^3-x^2=x^3-3x^2+3x-1` 

⇒ `2x^2-3x+1=0`  which is a quadratic equation