If $(1-p)$ is a root of quadratic equation $x^2+p x+(1-p)=0$, then its roots are

If $(1-p)$ is a root of quadratic equation $x^2+p x+(1-p)=0$, then its roots are
  1. 0,1
  2. $-1,2$
  3. $0,-1$
  4. $-1,1$

Solution

(3) $ \begin{aligned} & (1-p)^2+p(1-p)+(1-p)=0 \quad\left(\text { since }(1-p) \text { is a root of the equation } x^2+p x+(1-p)=0\right) \\ & \Rightarrow(1-p)(1-p+p+1)=0 \\ & \Rightarrow 2(1-p)=0 \Rightarrow(1-p)=0 \Rightarrow p=1 \\ & \text { sum of root is } \alpha+\beta=-p \text { and product } \alpha \beta=1-p=0 \quad \text { (where } \beta=1-p=0) \\ & \Rightarrow \alpha+0=-1 \Rightarrow \alpha=-1 \Rightarrow \text { Roots are } 0,-1 \end{aligned} $

Asked in: JEE Main 2004

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