·ÖÎö £¨¢ñ£©ÒÀÌâÒâÿÄêͶÈë¹¹³ÉÊ×ÏîΪ800ÍòÔª£¬¹«±ÈΪ$\frac{4}{5}$µÄµÈ±ÈÊýÁУ¬Ã¿ÄêÂÃÓÎÒµÊÕÈë×éÖ¯Ê×ÏîΪ400ÍòÔª£¬¹«±ÈΪ$\frac{5}{4}$µÄµÈ±ÈÊýÁУ¬½ø¶øÇó³öan£¬bnµÄ±í´ïʽ£®
£¨¢ò£©ÏÈÉèÖÁÉÙ¾¹ýnÄêÂÃÓÎÒµµÄ×ÜÊÕÈë²ÅÄܳ¬¹ý×ÜͶÈ룬ÓÉbn-an£¾0£¬½âµÃnµÄÈ¡Öµ·¶Î§¼´¿É£®
½â´ð £¨¢ñ£©½â£¬ÒÀÌâÒâÿÄêͶÈë¹¹³ÉÊ×ÏîΪ800ÍòÔª£¬¹«±ÈΪ$\frac{4}{5}$µÄµÈ±ÈÊýÁУ¬Ã¿ÄêÂÃÓÎÒµÊÕÈë×éÖ¯Ê×ÏîΪ400ÍòÔª£¬¹«±ÈΪ$\frac{5}{4}$µÄµÈ±ÈÊýÁУ®
ËùÒÔ£¬${a_n}=800•{£¨\frac{4}{5}£©^{n-1}}£¬\;{b_n}=400{£¨\frac{5}{4}£©^{n-1}}$£¬
£¨¢ò£©½â£¬¾¹ýnÄ꣬×ÜÊÕͶÈë${s_n}=\frac{{800£¨1-{{£¨\frac{4}{5}£©}^n}£©}}{{1-\frac{4}{5}}}=4000£¨1-{£¨\frac{4}{5}£©^n}£©$£¬
¾¹ýnÄ꣬×ÜÊÕÈë${T_n}=\frac{{400£¨1-{{£¨\frac{5}{4}£©}^n}£©}}{{1-\frac{5}{4}}}=1600£¨{£¨\frac{5}{4}£©^n}-1£©$£¬
Éè¾¹ýnÄ꣬×ÜÊÕÈ볬¹ý×ÜͶÈ룬ÓÉ´Ë£¬Tn-Sn£¾0£¬$1600£¨{£¨\frac{5}{4}£©^n}-1£©$$-4000£¨1-{£¨\frac{4}{5}£©^n}£©$£¾0£¬
»¯¼òµÃ $5•{£¨\frac{4}{5}£©^n}+2•{£¨\frac{5}{4}£©^n}-7£¾0$£¬
Éè$x={£¨\frac{4}{5}£©^n}$´úÈëÉÏʽÕûÀíµÃ£¬5x2-7x+2£¾0£¬
½âµÃ£¬$x£¼\frac{2}{5}$£¬»òx£¾1£¨ÉáÈ¥£©£¬
ÓÉ${£¨\frac{4}{5}£©^n}£¼\frac{2}{5}$£¬n=4ʱ£¬${£¨\frac{4}{5}£©^n}$=$\frac{256}{625}$$£¾\frac{2}{5}$£¬n=5£¬${£¨\frac{4}{5}£©^n}$=$\frac{1024}{3125}£¼\frac{2}{5}$£¬
ÒòΪ $y={£¨\frac{4}{5}£©^x}$ÔÚ¶¨ÒåÓòÉÏÊǼõº¯Êý£¬ËùÒÔ n¡Ý5£¬
´ð£ºÖÁÉÙ¾¹ý5ÄêÂÃÓÎÒµµÄ×ÜÊÕÈ볬¹ý×ÜͶÈ룮
µãÆÀ ±¾Ð¡ÌâÖ÷Òª¿¼²éÊýÁеĻù±¾Ó¦Óá¢ÊýÁÐÇóºÍ¡¢²»µÈʽµÈ»ù´¡ÖªÊ¶£»¿¼²é×ÛºÏÔËÓÃÊýѧ֪ʶ½â¾öʵ¼ÊÎÊÌâµÄÄÜÁ¦£¬ÊôÓÚÖеµÌ⣮
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£ºÑ¡ÔñÌâ
A£® | 135¡ã | B£® | 150¡ã | C£® | 90¡ã | D£® | 120¡ã |
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ
A£® | 4x¡ä2+9y¡ä2=1 | B£® | $\frac{{{{x'}^2}}}{2}+\frac{{{{y'}^2}}}{3}=1$ | C£® | $\frac{{{{x'}^2}}}{9}+\frac{{{{y'}^2}}}{4}=1$ | D£® | $\frac{{{{x'}^2}}}{4}+\frac{{{{y'}^2}}}{9}=1$ |
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£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£® | £¨-3£¬0£© | B£® | £¨3£¬0£© | C£® | £¨2£¬0£© | D£® | £¨4£¬0£© |
²é¿´´ð°¸ºÍ½âÎö>>
¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ
A£® | ÊǵȲîÊýÁУ¬µ«²»ÊǵȱÈÊýÁÐ | B£® | ÊǵȱÈÊýÁУ¬µ«²»ÊǵȲîÊýÁÐ | ||
C£® | ¼ÈÊǵȲîÊýÁУ¬ÓÖÊǵȱÈÊýÁÐ | D£® | ·ÇµÈ²îÊýÁУ¬ÓַǵȱÈÊýÁÐ |
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