²é¿´: 1122  |  »Ø¸´: 10
µ±Ç°Ö»ÏÔʾÂú×ãÖ¸¶¨Ìõ¼þµÄ»ØÌû£¬µã»÷ÕâÀï²é¿´±¾»°ÌâµÄËùÓлØÌû

linda_nm

гæ (³õÈëÎÄ̳)

[ÇóÖú] Çë½ÌÊýѧÐòÁÐÇóºÍÎÊÌâ! ÒÑÓÐ3È˲ÎÓë

Çë½ÌÒ»¸öÐòÁÐ(1)^2,(1+a)^2,(1+a+a^2)^2, ..., (+a+a^2+a^3+..+a^k)^2µÄºÍʽ×Ó

[ Last edited by feixiaolin on 2014-12-21 at 12:05 ]
»Ø¸´´ËÂ¥

» ²ÂÄãϲ»¶

» ±¾Ö÷ÌâÏà¹Ø¼ÛÖµÌùÍÆ¼ö£¬¶ÔÄúͬÑùÓаïÖú:

ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

wurongjun

ר¼Ò¹ËÎÊ (Ö°Òµ×÷¼Ò)

¡¾´ð°¸¡¿Ó¦Öú»ØÌû

¡ï ¡ï ¡ï ¡ï
¸Ðл²ÎÓ룬ӦÖúÖ¸Êý +1
feixiaolin: ½ð±Ò+4 2014-12-21 14:51:57
>> syms k
>> symsum(a^k,k,0,k)
ans =
a^(k+1)/(a-1)-1/(a-1)
>> factor(ans)
ans =
(a^(k+1)-1)/(a-1)
>> symsum((a^(k+1)-1)/(a-1),k,0,k)
ans =
-(-a^(k+1)*a+(k+1)*a-k-1)/(a-1)^2-a/(a-1)^2
>> factor(ans)
ans =
-(-a^(k+1)*a+k*a+2*a-k-1)/(a-1)^2
ÉÆ¶ñµ½Í·ÖÕÓб¨,È˼äÕýµÀÊDz×É£.
4Â¥2014-12-21 12:12:55
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
²é¿´È«²¿ 11 ¸ö»Ø´ð

zaq123321

ר¼Ò¹ËÎÊ (ÖøÃûдÊÖ)

¡¾´ð°¸¡¿Ó¦Öú»ØÌû

¡ï ¡ï ¡ï ¡ï ¡ï
¸Ðл²ÎÓ룬ӦÖúÖ¸Êý +1
linda_nm(feixiaolin´ú·¢): ½ð±Ò+5 2014-12-21 14:51:48
Can you double check whether the third item is (1+a+a^2)^2 or not? If that's true, it will be the sum of squared geometric series. Should be not complicated. Good luck.

[ ·¢×ÔÊÖ»ú°æ http://muchong.com/3g ]
Сľ³æ¸øÎÒÎÂů£¬¸øÎÒÏ£Íû£¬°®¾ÍÒª°®Ð¡Ä¾³æ¡£
2Â¥2014-12-21 10:28:01
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

feixiaolin

ÈÙÓþ°æÖ÷ (ÎÄ̳¾«Ó¢)

ÓÅÐã°æÖ÷

ÿһÏî*(1-a)^2/(1-a)^2£¬¼ò»¯·Ö×Ó±í´ïʽ£¬ÔÙÏà¼Ó

» ±¾ÌûÒÑ»ñµÃµÄºì»¨£¨×îÐÂ10¶ä£©

3Â¥2014-12-21 12:06:12
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

linda_nm

гæ (³õÈëÎÄ̳)

ÒýÓûØÌû:
2Â¥: Originally posted by zaq123321 at 2014-12-21 10:28:01
Can you double check whether the third item is (1+a+a^2)^2 or not? If that's true, it will be the sum of squared geometric series. Should be not complicated. Good luck.
...

ÕýÊÇ(1+a+a^2)^2
5Â¥2014-12-21 13:41:17
ÒÑÔÄ   »Ø¸´´ËÂ¥   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
×î¾ßÈËÆøÈÈÌûÍÆ¼ö [²é¿´È«²¿] ×÷Õß »Ø/¿´ ×îºó·¢±í
[¿¼ÑÐ] 289Çóµ÷¼Á +16 ˶ÐǸ° 2026-03-23 16/800 2026-03-26 13:18 by ССÂóƬ
[¿¼ÑÐ] Ò»Ö¾Ô¸¹þ¹¤´ó£¬085400£¬320£¬Çóµ÷¼Á +4 gdlf9999 2026-03-24 4/200 2026-03-25 23:01 by boxking200
[¿¼ÑÐ] 07»¯Ñ§303Çóµ÷¼Á +5 î£08 2026-03-25 5/250 2026-03-25 22:46 by 418490947
[¿¼ÑÐ] ²ÄÁÏѧ˶333Çóµ÷¼Á +4 ±±µÀÏï 2026-03-24 4/200 2026-03-25 14:16 by mapenggao
[¿¼ÑÐ] 0703»¯Ñ§µ÷¼Á£¬Çóµ¼Ê¦ÊÕ +7 ÌìÌìºÃÔËÀ´Éϰ¶° 2026-03-24 7/350 2026-03-24 20:26 by peike
[¿¼ÑÐ] Ò»Ö¾Ô¸±±»¯315 Çóµ÷¼Á +3 akrrain 2026-03-24 3/150 2026-03-24 19:35 by ÁËÁËÁËÁË¡£¡£
[¿¼ÑÐ] ²ÄÁÏ292µ÷¼Á +8 éÙËÌ˼ÃÀÈË 2026-03-23 8/400 2026-03-24 16:33 by laoshidan
[¿¼²©] 26É격×Ô¼ö +3 whh869393 2026-03-24 3/150 2026-03-24 09:55 by 21018060
[¿¼ÑÐ] Ò»Ö¾Ô¸ºÓ±±¹¤Òµ´óѧ0817»¯¹¤278·ÖÇóµ÷¼Á +7 jhybd 2026-03-23 12/600 2026-03-24 09:03 by jhybd
[¿¼ÑÐ] »·¾³Ñ§Ë¶288Çóµ÷¼Á +8 ƤƤƤ123456 2026-03-22 8/400 2026-03-23 23:47 by ÈÈÇéɳĮ
[¿¼ÑÐ] 284Çóµ÷¼Á +3 yanzhixue111 2026-03-23 6/300 2026-03-23 22:58 by pswait
[¿¼ÑÐ] 361Çóµ÷¼Á +3 Glack 2026-03-22 3/150 2026-03-23 22:03 by fuyu_
[¿¼ÑÐ] 384Çóµ÷¼Á +3 ×Óϵ²© 2026-03-22 6/300 2026-03-23 21:45 by ×Óϵ²©
[¿¼ÑÐ] Çóµ÷¼ÁÒ»Ö¾Ô¸º£´ó£¬0703»¯Ñ§Ñ§Ë¶304·Ö£¬Óдó´´ÏîÄ¿£¬Ëļ¶Òѹý +6 ÐÒÔËÁ¨Á¨ 2026-03-22 10/500 2026-03-22 20:10 by edmund7
[¿¼ÑÐ] Ò»Ö¾Ô¸»ªÖÐũҵ071010£¬×Ü·Ö320Çóµ÷¼Á +5 À§À§À§À§À¤À¤ 2026-03-20 6/300 2026-03-22 17:41 by hxsm
[¿¼ÑÐ] 306Çóµ÷¼Á +5 À´ºÃÔËÀ´À´À´ 2026-03-22 5/250 2026-03-22 16:17 by BruceLiu320
[¿¼ÑÐ] ²ÄÁÏÓ뻯¹¤£¨0856£©304ÇóBÇøµ÷¼Á +3 Çñgl 2026-03-20 7/350 2026-03-21 19:05 by 15709483992
[¿¼ÑÐ] 336Çóµ÷¼Á +5 rmc8866 2026-03-21 5/250 2026-03-21 17:24 by ѧԱ8dgXkO
[¿¼ÑÐ] 295¸´ÊÔµ÷¼Á +8 ¼òľChuFront 2026-03-19 8/400 2026-03-20 20:44 by zhukairuo
[¿¼ÑÐ] Çóµ÷¼Á +3 @taotao 2026-03-20 3/150 2026-03-20 19:35 by JourneyLucky
ÐÅÏ¢Ìáʾ
ÇëÌî´¦ÀíÒâ¼û