Let α and β be the roots of the equation p x^2+q x-r=0, where p ≠ 0. If p, q and r be the consecutive terms of a non constant G.P. and…

Let $\displaystyle \alpha$ and $\displaystyle \beta$ be the roots of the equation $\displaystyle p x^2+q x-r=0$, where $\displaystyle p \neq 0$. If $\displaystyle p$, $\displaystyle q$ and $\displaystyle r$ be the consecutive terms of a non constant G.P. and $\displaystyle \frac{1}{\alpha}+\frac{1}{\beta}=\frac{3}{4}$, then the value of $\displaystyle (\alpha-\beta)^2$ is :