• 415 ｢1/n² Σn=1,∞｣
ᐥ｢1/n² Σn=1,∞｣ convergesᐥ ｢1/n² Σn=1,∞｣ = 1/1² + 1/2² + (1/3²+1/4²) + (1/5²+1/6²+1/7²+1/8²) + ... < 1/1² + 1/2 + (1/2²+1/2²) + (1/4²+1/4²+1/4²+1/4²) + ... ┄ 1/(2˄(k−2))²·2˄(k−2) = 1/2˄(2k−4)·2˄(k−2) = 1/2˄(2k−4−k+2) = 1/2˄(k−2) ┄ = 1 + 1/2˄0 + 1/2˄1 + 1 ...
http://qindex.info/i.php?x=24853