sum from n=1 to infinity of 9/n-9/(n^2)

解答

n = 1 \sum \infty \frac{9}{n} - \frac{9}{n ^{2}}

发散

求解步骤

n = 1 \sum \infty \frac{9}{n} - \frac{9}{n ^{2}}

使用级数积分审敛法:

发散

= 发散

n = 3 \sum \infty arctan (n)

n = 1 \sum \infty \frac{1}{( 4 n ) !}

n = 1 \sum \infty \frac{1}{2 n + 2}

n = 0 \sum \infty \frac{5}{0. 5 ^{n} - 2}

n = 0 \sum \infty \frac{2 ^{n}}{n ^{7}}