. Let a and b be the roots of equation px2 + qx + r = 0, p ¹ 0. If p, q, r are in A.P and 1 1 + a b = 4, then the value of | a – b| is:

Let $\alpha$ and $\beta$ be the roots of equation $\mathrm{px}^{2}+\mathrm{qx}+\mathrm{r}=0, \mathrm{p} \neq 0$

If $p, q, r$ are in A.P and $\frac{1}{\alpha}+\frac{1}{\beta}=4$, then the value of $|\alpha-\beta|$ is: