Here is the problem:

2. The power series for e-, below, converges for all r and is alternating for all > > 0. =1-r+ +.... 2! 3! n! Given a fixed r > 0, how large can n be chosen so that the n-th partial sum for e- Sn=1-I+ 2! 3! n! be so that the error S, - e-3 |