µ±x>
1ʱ£¬Ô²»µÈʽ¿É»¯Îªx+2x¨C1>2£¬½âµÃx>1. 2×ÛÉÏ£¬Ô²»µÈʽµÄ½â¼¯Îª{x|x??»òx?1}.
1322.¡¾±Ø×öÌâ¡¿±¾Ð¡ÌâÖ÷Òª¿¼²é¶þÏîʽ¶¨Àí¡¢×éºÏÊýµÈ»ù´¡ÖªÊ¶£¬¿¼²é·ÖÎöÎÊÌâÄÜÁ¦ÓëÔËËãÇó½âÄÜÁ¦£¬Âú·Ö
10·Ö£®
½â£º£¨1£©ÒòΪ(1?x)n?C0n?C1nx?C2nx2?L?Cnnnx£¬n?4£¬ ËùÒÔa1)2?C2n(n?n?2,an(n?1)(n?2)3?C3n?6£¬ an(n?1)(n?2)(n?3)4?C4n?24£®
ÒòΪa23?2a2a4£¬
ËùÒÔ[n(n?1)(n?2)2n(n?1)n(n?1)(n?2)(n?6]?2?2?3)24£¬
½âµÃn?5£®
£¨2£©ÓÉ£¨1£©Öª£¬n?5£®
(1?3)n?(1?3)5
?C0223344555?C153?C5(3)?C5(3)?C5(3)?C5(3) ?a?b3£®
½â·¨Ò»£º
ÒòΪa,b?N*£¬ËùÒÔa?C02413C355?3C5?9C5?76,b?C5?5?9C5?44£¬´Ó¶øa2?3b2?762?3?442??32£®
ʵ Óà ÎÄ µµ
21
½â·¨¶þ£º
022334455 (1?3)5?C5?C15(?3)?C5(?3)?C5(?3)?C5(?3)?C5(?3)022334455£® ?C5?C153?C5(3)?C5(3)?C5(3)?C5(3)ÒòΪa,b?N£¬ËùÒÔ(1?3)5?a?b3£®
*Òò´Ëa2?3b2?(a?b3)(a?b3)?(1?3)5?(1?3)5?(?2)5??32£®
23£®¡¾±Ø×öÌâ¡¿±¾Ð¡ÌâÖ÷Òª¿¼²é¼ÆÊýÔÀí¡¢¹Åµä¸ÅÐÍ¡¢Ëæ»ú±äÁ¿¼°Æä¸ÅÂÊ·Ö²¼µÈ»ù´¡ÖªÊ¶£¬¿¼²éÂ߼˼ά
ÄÜÁ¦ºÍÍÆÀíÂÛÖ¤ÄÜÁ¦£®Âú·Ö10·Ö£®
½â£º£¨1£©µ±n?1ʱ£¬XµÄËùÓпÉÄÜȡֵÊÇ1£¬2£¬2£¬5£®
XµÄ¸ÅÂÊ·Ö²¼ÎªP(X?1)?7744?,P(X?2)??£¬ 22C615C615P(X?2)?2222?,P(X?5)??£® 22C615C615b)ºÍB(c£¬d)ÊÇ´ÓMnÖÐÈ¡³öµÄÁ½¸öµã£® £¨2£©ÉèA(a£¬ÒòΪP(X?n)?1?P(X?n)£¬ËùÒÔ½öÐ迼ÂÇX?nµÄÇé¿ö£® ¢ÙÈôb?d£¬ÔòAB?n£¬²»´æÔÚX?nµÄÈ¡·¨£»
d?1£¬ÔòAB?(a?c)2?1?¢ÚÈôb?0£¬a?0£¬ c?n»òa?n£¬ c?0£¬ÓÐ2ÖÖÈ¡·¨£»
n2?1£¬ËùÒÔX?nµ±ÇÒ½öµ±AB?n2?1£¬´Ëʱ
d?2£¬¢ÛÈôb?0£¬ÔòAB?(a?c)2?4?n2?4£¬ÒòΪµ±n?3ʱ£¬(n?1)2?4?n£¬ËùÒÔX?n c?n»òa?n£¬ c?0£¬ÓÐ2ÖÖÈ¡·¨£» µ±ÇÒ½öµ±AB?n2?4£¬´Ëʱa?0£¬d?2£¬ÔòAB?(a?c)2?1?¢ÜÈôb?1£¬n2?1£¬ËùÒÔX?nµ±ÇÒ½öµ±AB?n2?1£¬´Ëʱ
22
ʵ Óà ÎÄ µµ
a?0£¬ c?n»òa?n£¬ c?0£¬ÓÐ2ÖÖÈ¡·¨£®
×ÛÉÏ£¬µ±X?nʱ£¬XµÄËùÓпÉÄÜȡֵÊÇn2?1ºÍn2?4£¬ÇÒ
P(X?n2?1)?4C2,P(X?n2?4)?22n?4C2£®
2n?4Òò´Ë£¬P(X?n)?1?P(X?n2?1)?P(X?n2?4)?1?6C2£®2n?4
ʵ Óà ÎÄ µµ 23