I attempted to solve this problem:
Determine the values of $x$ for which the function can be replaced by the Taylor polynomial if the error cannot exceed $0.001$.
I thought this equation went to $n=4$, so when using Lagrange Error, I found the max of the fifth derivative ($n+1=4+1=5$). However, I found out it was wrong; actually, this equation went to $n=5$ and I should find the max of the sixth derivative for Lagrange Error. Why is that? It seems not to follow the $n+1$ rule for Lagrange Error.