If lim_x → 1^+ ((x-1)(6+λ cos (x-1))+μ sin (1-x))/((x-1)^3)=-1, where λ, μ ∈ R, then λ+μ is equal to

If $\displaystyle \lim _{x \rightarrow 1^{+}} \frac{(x-1)(6+\lambda \cos (x-1))+\mu \sin (1-x)}{(x-1)^3}=-1$, where $\displaystyle \lambda, \mu \in \mathbb{R}$, then $\displaystyle \lambda+\mu$ is equal to