1−x1excosxsinxln(1+x)arctanx=n=0∑∞xn=n=0∑∞n!xn=n=0∑∞(2n)!(−1)nx2n=n=1∑∞(2n−1)!(−1)n−1x2n−1=n=1∑∞n(−1)n−1xn=n=1∑∞2n−1(−1)n−1x2n−1=1+x+x2+x3+…=1+x+2!x2+3!x3+…=1−2!x2+4!x4−6!x6+…=x−3!x3+5!x5−7!x7+…=x−2x2+3x3−4x4+…=x−3x3+5x5−7x7+…