·ÖÎö £¨1£©¸ù¾Ý$a_n^2-{a_n}{a_{n-1}}-2n{a_{n-1}}-4{n^2}=0$£¬£¨n¡Ý2£¬n¡ÊN£©Ð´³ö´ð°¸¼´¿É£»
£¨2£©ÓÉÒÑÖªÌõ¼þµÃµ½£¨an+2n£©£¨an-an-1-2n£©=0£¬ÓÉ´ËÇóµÃ${a_n}-{a_{n-1}}-2n=0\begin{array}{l}{\;}{£¨n£¾2£©}\end{array}$£¬ËùÒÔan=£¨an-an-1£©+£¨an-1-an-2£©+¡+£¨a2-a1£©+a1£»
£¨3£©ÀûÓÃÁÑÏî·¨ÇóµÃbn=$\frac{1}{£¨2n+\frac{1}{n}£©}+3$£¬È»ºóÀûÓû»Ôª·¨µÃµ½Áî$f£¨x£©=2x+\frac{1}{x}$£¨x¡Ý1£©£¬ÔòÆäµ¼º¯ÊýΪ$f'£¨x£©=2-\frac{1}{x^2}¡Ý2-1£¾0$£¬½áºÏº¯ÊýµÄµ¥µ÷ÐÔ½øÐнâ´ð£®
½â´ð ½â£º£¨1£©a2=6£¬a3=12£»
£¨2£©ÓÉÒÑÖª¿ÉµÃ£º£¨an-2n£©£¨an+2n£©-an-1£¨an+2n£©=0£¬
¡à£¨an+2n£©£¨an-an-1-2n£©=0£¬
ÓÖan£¾0£¬
¡à${a_n}-{a_{n-1}}-2n=0\begin{array}{l}{\;}{£¨n£¾2£©}\end{array}$£¬
¡àan=£¨an-an-1£©+£¨an-1-an-2£©+¡+£¨a2-a1£©+a1=2+4+6+¡+2n=n£¨n+1£©£»
£¨3£©${b_n}=\frac{1}{{{a_{n+1}}}}+\frac{1}{{{a_{n+2}}}}+\frac{1}{{{a_{n+3}}}}+¡+\frac{1}{{{a_{2n}}}}$
=$\frac{1}{£¨n+1£©£¨n+2£©}+\frac{1}{£¨n+2£©£¨n+3£©}+¡+\frac{1}{2n£¨2n+1£©}$
=$\frac{1}{n+1}-\frac{1}{2n+1}=\frac{n}{{2{n^2}+3n+1}}=\frac{1}{{£¨2n+\frac{1}{n}£©+3}}$£®
Áî$f£¨x£©=2x+\frac{1}{x}$£¨x¡Ý1£©£¬Ôò$f'£¨x£©=2-\frac{1}{x^2}¡Ý2-1£¾0$£¬
ËùÒÔf£¨x£©ÔÚ[1£¬+¡Þ£©ÉÏÊÇÔöº¯Êý£¬
¹Êµ±x=1ʱ£¬f£¨x£©È¡µÃ×îСֵ3£¬¼´µ±n=1ʱ£¬${£¨{b_n}£©_{max}}=\frac{1}{6}$£®
${t^2}-2mt+\frac{1}{6}£¾{b_n}$£¨?n¡ÊN*£¬?m¡Ê[-1£¬1]£©$?{t^2}-2mt+\frac{1}{6}£¾{£¨{b_n}£©_{max}}=\frac{1}{6}$£¬
¼´t2-2mt£¾0£¨?m¡Ê[-1£¬1]£©$?\left\{\begin{array}{l}{t^2}-2t£¾0\\{t^2}+2t£¾0\end{array}\right.$£®
½âÖ®µÃ£¬ÊµÊýtµÄÈ¡Öµ·¶Î§Îª£¨-¡Þ£¬-2£©¡È£¨2£¬+¡Þ£©£®
µãÆÀ ¿¼²éÊýÁеÄͨÏʽµÄÇ󷨣¬¿¼²éʵÊýµÄÈ¡Öµ·¶Î§µÄÇ󷨣¬ÊÇÖеµÌ⣬½âÌâʱҪÈÏÕæÉóÌ⣬עÒ⺯ÊýÐÔÖʵĺÏÀíÔËÓã®
Ä꼶 | ¸ßÖÐ¿Î³Ì | Ä꼶 | ³õÖÐ¿Î³Ì |
¸ßÒ» | ¸ßÒ»Ãâ·Ñ¿Î³ÌÍƼö£¡ | ³õÒ» | ³õÒ»Ãâ·Ñ¿Î³ÌÍƼö£¡ |
¸ß¶þ | ¸ß¶þÃâ·Ñ¿Î³ÌÍƼö£¡ | ³õ¶þ | ³õ¶þÃâ·Ñ¿Î³ÌÍƼö£¡ |
¸ßÈý | ¸ßÈýÃâ·Ñ¿Î³ÌÍƼö£¡ | ³õÈý | ³õÈýÃâ·Ñ¿Î³ÌÍƼö£¡ |
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÌî¿ÕÌâ
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£º½â´ðÌâ
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ
A£® | 2$\sqrt{3}$ | B£® | $\sqrt{7}$ | C£® | $\sqrt{3}$ | D£® | 3 |
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ
A£® | 1 | B£® | 2 | C£® | 4 | D£® | 6 |
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ
A£® | 2 | B£® | 3 | C£® | 4 | D£® | 5 |
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£º½â´ðÌâ
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£º½â´ðÌâ
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ
A£® | Èô¦Á¡Í¦Â£¬Ôòm¡Ín | B£® | Èô¦Á¡Î¦Â£¬Ôòm¡În | C£® | Èôm¡Ín£¬Ôò¦Á¡Í¦Â | D£® | Èôn¡Í¦Á£¬Ôò¦Á¡Í¦Â |
²é¿´´ð°¸ºÍ½âÎö>>
°Ù¶ÈÖÂÐÅ - Á·Ï°²áÁбí - ÊÔÌâÁбí
ºþ±±Ê¡»¥ÁªÍøÎ¥·¨ºÍ²»Á¼ÐÅÏ¢¾Ù±¨Æ½Ì¨ | ÍøÉÏÓк¦ÐÅÏ¢¾Ù±¨×¨Çø | µçÐÅթƾٱ¨×¨Çø | ÉæÀúÊ·ÐéÎÞÖ÷ÒåÓк¦ÐÅÏ¢¾Ù±¨×¨Çø | ÉæÆóÇÖȨ¾Ù±¨×¨Çø
Î¥·¨ºÍ²»Á¼ÐÅÏ¢¾Ù±¨µç»°£º027-86699610 ¾Ù±¨ÓÊÏ䣺58377363@163.com