1+2+3+4+ +n =n*(n+1)/2=(n^2+n)/2 设æ¤æ°ä¸ºT1åæn^2+n=2T1
èåé¢çå¼å为ï¼n^2+n-1=2T1-1
ç°åªéè¯æ1+1/2+1/3+â¦+1/nç大å°äºï¼è®¾æ¤æ°ä¸ºMï¼åæï¼
T1*M=2T1-1
M=(2T1-1)/T1=2-1/T1<2
æ¤æ¶ï¼ç»æå·²åºæ¥äºï¼å 1+1/2+1/3+1/4+ +
=1+ï¼1/2+1/3+1/4ï¼+ï¼1/5+1/6+1/7+1/8+1/9+1/10+1/11+1/12+ ï¼
=1+1+1+ >2>M æ¤å¼åä¹å¾å¥½æï¼å 为æ»æn个1/nç¸å å°±ä¼çäº1ï¼å¦1+3个1/3+14个1/14个ï¼æ¤æ¶nå°äº14äºï¼+
ç°å¨è¯æç¸ççæ
åµï¼å½n=3æ¶ï¼ä¸¤å¼ç¸çã
è¯æå®æ¯ï¼ï¼
温馨提示:答案为网友推荐,仅供参考