Hi

Just to clarify something

If the given question was to find the Laurent Series of $\displaystyle \frac{1}{z^2-7z+10}$ would you find the valid regions by using$\displaystyle \frac{1}{z-2} + \frac{1}{z-5}$ or use the partial expansion form $\displaystyle \frac{1}{3(z-5)}- \frac{1}{3(z-2)}$

P.S