If α, β and γ are three consecutive terms of a non-constant G.P. such that the equations α x^2+2 β x+γ=0 and x^2+x-1=0 have a common root, then…

If $\displaystyle \alpha, \beta$ and $\displaystyle \gamma$ are three consecutive terms of a non-constant G.P. such that the equations $\displaystyle \alpha x^2+2 \beta x+\gamma=0$ and $\displaystyle x^2+x-1=0$ have a common root, then $\displaystyle \alpha(\beta+\gamma)$ is equal to :