$$\sum_{k=0}^{n-1}\frac{\left [ (x-b)+(b-a) \right ]^k}{k!}$$
the below equation is derived from the above equation . Could anyone you please explain how did the author solved it . I'm learning fractional calculus for my research
$$\sum_{j=0}^{k}\frac{[x-b]^j[b-a]^{k-j}}{j!(k-j)!}$$