Let a_1, a_2, a_3, … be a G. P. such that a_1<0, a_1+a_2=4 and a_3+a_4=16. If Σ_i=1^9 a_i=4 λ, then λ is equal to:

Let $\displaystyle \mathrm{a}_1, \mathrm{a}_2, \mathrm{a}_3, \ldots$ be a G. P. such that $\displaystyle \mathrm{a}_1<0$, $\displaystyle a_1+a_2=4$ and $\displaystyle a_3+a_4=16$. If $\displaystyle \sum_{i=1}^9 a_i=4 \lambda$, then $\displaystyle \lambda$ is equal to :