JEE-Mains 2014 (4/30)

Algebra Level 3

Let $\alpha$ and $\beta$ be the roots of equation $px^2+qx+r \ , \ p \neq 0$ . If $p,q,r$ are in arithmetic progression and $\frac{1}{\alpha}+\frac{1}{\beta}=4$ , then the value of $|\alpha-\beta|$ is :