Which series represents cos(x)\cos(x)cos(x) centered at a=0a=0a=0?
∑n=0∞(−1)nxnn!\sum_{n=0}^{\infty} \frac{(-1)^n x^n}{n!}∑n=0∞n!(−1)nxn
∑n=0∞(−1)nx2n(2n)!\sum_{n=0}^{\infty} \frac{(-1)^n x^{2n}}{(2n)!}∑n=0∞(2n)!(−1)nx2n
∑n=0∞x2n(2n)!\sum_{n=0}^{\infty} \frac{x^{2n}}{(2n)!}∑n=0∞(2n)!x2n
∑n=0∞(−1)nx2n(2n+1)!\sum_{n=0}^{\infty} \frac{(-1)^n x^{2n}}{(2n+1)!}∑n=0∞(2n+1)!(−1)nx2n