çæ¯æ°åæ±åå
¬å¼
(1) çæ¯æ°åï¼a (n+1)/an=q (nâN).
(2) é项å
¬å¼ï¼an=a1Ãq^(n-1)ï¼ æ¨å¹¿å¼ï¼an=amÃq^(n-m)ï¼
(3) æ±åå
¬å¼ï¼Sn=nÃa1 (q=1) Sn=a1(1-q^n)/(1-q) =(a1-anÃq)/(1-q) (qâ 1) (q为å
¬æ¯,n为项æ°ï¼
(4)æ§è´¨ï¼
â è¥ mãnãpãqâN,ä¸mï¼n=pï¼q,åamÃan=apÃaqï¼
â¡å¨çæ¯æ°åä¸,ä¾æ¬¡æ¯ k项ä¹åä»æçæ¯æ°å.
â¢è¥mãnãqâN,ä¸m+n=2q,åamÃan=aq^2
(5)"Gæ¯aãbççæ¯ä¸é¡¹""G^2=abï¼G â 0ï¼".
(6)å¨çæ¯æ°åä¸,é¦é¡¹a1ä¸å
¬æ¯qé½ä¸ä¸ºé¶.注æï¼ä¸è¿°å
¬å¼ä¸an表示çæ¯æ°åç第n项.çæ¯æ°åæ±åå
¬å¼æ¨å¯¼ï¼Sn=a1+a2+a3+...+an(å
¬æ¯ä¸ºq) q*Sn=a1*q+a2*q+a3*q+...+an*q =a2+a3+a4+...+a(n+1) Sn-q*Sn=a1-a(n+1) (1-q)Sn=a1-a1*q^n Sn=(a1-a1*q^n)/(1-q) Sn=(a1-an*q)/(1-q) Sn=a1(1-q^n)/(1-q) Sn=k*(1-q^n)~y=k*(1-a^x)
温馨提示:答案为网友推荐,仅供参考