# Math Help - can someone identify this

1. ## can someone identify this

$R_n(x)=\frac{1}{2\pi i} \int_C \frac{f(z)}{(z-a)^{n-1}(z-x)} dz$

What is this and what is it used for?

2. It's a formula dealing with the remainder term in a complex Taylor Series.

Look at this Wikipedia entry - Taylor's theorem - Wikipedia, the free encyclopedia