13£®Àí¿Æ¾ºÈüС×éÓÐ9ÃûÅ®Éú¡¢12ÃûÄÐÉú£¬´ÓÖÐËæ»ú³éȡһ¸öÈÝÁ¿Îª7µÄÑù±¾½øÐзÖÎö£®
£¨¢ñ£©Èç¹û°´ÕÕÐÔ±ð±ÈÀý·Ö²ã³éÑù£¬¿ÉÒԵõ½¶àÉÙ¸ö²»Í¬µÄÑù±¾£¿£¨Ð´³öËãʽ¼´¿É£©
£¨¢ò£©Èç¹ûËæ»ú³éÈ¡µÄ7ÃûͬѧµÄÎïÀí¡¢»¯Ñ§³É¼¨£¨µ¥Î»£º·Ö£©¶ÔÓ¦Èç±í£º
 Ñ§ÉúÐòºÅ 1 2 3 4 5 6 7
 ÎïÀí³É¼¨ 65 70 75 81 85 87 93
 »¯Ñ§³É¼¨ 72 68 80 85 90 86 91
¹æ¶¨85·ÖÒÔÉÏ£¨°üÀ¨85·Ý£©ÎªÓÅÐ㣬´ÓÕâ7ÃûͬѧÖÐÔÙ³éÈ¡3Ãûͬѧ£¬¼ÇÕâ3ÃûͬѧÖÐÎïÀíºÍ»¯Ñ§³É¼¨¾ùΪÓÅÐãµÄÈËÊýΪX£¬ÇóËæ»ú±äÁ¿XµÄ·Ö²¼ÁкÍÊýѧÆÚÍû£®

·ÖÎö £¨¢ñ£©Èç¹û°´ÕÕÐÔ±ð±ÈÀý·Ö²ã³éÑù£¬Ôò´Ó9ÃûÅ®Éú¡¢12ÃûÄÐÉú£¬´ÓÖÐËæ»ú³éȡһ¸öÈÝÁ¿Îª7µÄÑù±¾£¬³éÈ¡µÄÅ®ÉúΪ3ÈË£¬ÄÐÉúΪ4ÈË£®ÀûÓÃ×éºÏÊýµÄÒâÒå¼´¿ÉµÃ³ö£®
£¨II£©Õâ7ÃûͬѧÖÐÎïÀíºÍ»¯Ñ§³É¼¨¾ùΪÓÅÐãµÄÈËÊýΪ3ÈË£¬³éÈ¡µÄ3ÃûͬѧÖÐÎïÀíºÍ»¯Ñ§³É¼¨¾ùΪÓÅÐãµÄÈËÊýX¿ÉÄÜȡֵΪ0£¬1£¬2£¬3£¬¿ÉµÃP£¨X=k£©=$\frac{{∁}_{3}^{k}{∁}_{4}^{3-k}}{{∁}_{7}^{3}}$£¬¼´¿ÉµÃ³ö·Ö²¼ÁÐÓëÊýѧÆÚÍû¼ÆË㹫ʽ£®

½â´ð ½â£º£¨¢ñ£©Èç¹û°´ÕÕÐÔ±ð±ÈÀý·Ö²ã³éÑù£¬Ôò´Ó9ÃûÅ®Éú¡¢12ÃûÄÐÉú£¬
´ÓÖÐËæ»ú³éȡһ¸öÈÝÁ¿Îª7µÄÑù±¾£¬³éÈ¡µÄÅ®ÉúΪ3ÈË£¬ÄÐÉúΪ4ÈË£®¿ÉÒԵõ½${∁}_{9}^{3}{∁}_{12}^{4}$¸ö²»Í¬µÄÑù±¾£®
£¨II£©Õâ7ÃûͬѧÖÐÎïÀíºÍ»¯Ñ§³É¼¨¾ùΪÓÅÐãµÄÈËÊýΪ3ÈË£¬
³éÈ¡µÄ3ÃûͬѧÖÐÎïÀíºÍ»¯Ñ§³É¼¨¾ùΪÓÅÐãµÄÈËÊýX¿ÉÄÜȡֵΪ0£¬1£¬2£¬3£¬
ÔòP£¨X=k£©=$\frac{{∁}_{3}^{k}{∁}_{4}^{3-k}}{{∁}_{7}^{3}}$£¬¿ÉµÃP£¨X=0£©=$\frac{4}{35}$£¬P£¨X=1£©=$\frac{18}{35}$£¬P£¨X=2£©=$\frac{12}{35}$£¬P£¨X=3£©=$\frac{1}{35}$£®
ÆäX·Ö²¼ÁÐΪ£º

 X 0 1 2 3
 P $\frac{4}{35}$ $\frac{18}{35}$ $\frac{12}{35}$ $\frac{1}{35}$
ÊýѧÆÚÍûE£¨X£©=0+1¡Á$\frac{18}{35}$+2¡Á$\frac{12}{35}$+3¡Á$\frac{1}{35}$=$\frac{9}{7}$£®

µãÆÀ ±¾Ì⿼²éÁ˳¬¼¸ºÎ·Ö²¼ÁеĸÅÂÊÊýѧÆÚÍû¼°Æä·½²îµÄ¼ÆË㹫ʽ¡¢×éºÏÊýÓë³Ë·¨¼ÆÊýÔ­Àí¼ÆË㹫ʽ£¬¿¼²éÁËÍÆÀíÄÜÁ¦Óë¼ÆËãÄÜÁ¦£¬ÊôÓÚÖеµÌ⣮

Á·Ï°²áϵÁдð°¸
Ïà¹ØÏ°Ìâ

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£º½â´ðÌâ

20£®Ä³³¬Êо­ÓªÒ»Åú²úÆ·£¬ÔÚÊг¡ÏúÊÛÖз¢Ïִ˲úÆ·ÔÚ30ÌìÄÚµÄÈÕÏúÊÛÁ¿P£¨¼þ£©ÓëÈÕÆÚt£¨1¡Üt¡Ü30£¬t¡ÊN+£©£©Ö®¼äÂú×ãP=kt+b£¬ÒÑÖªµÚ5ÈÕµÄÏúÊÛÁ¿Îª55¼þ£¬µÚ10ÈÕµÄÏúÊÛÁ¿Îª50¼þ£®
£¨1£©ÇóµÚ20ÈÕµÄÏúÊÛÁ¿£»                
£¨2£©ÈôÏúÊÛµ¥¼ÛQ£¨Ôª/¼þ£©ÓëtµÄ¹ØÏµÊ½Îª$Q=\left\{\begin{array}{l}t+20£¬1¡Üt£¼25\\ 80-t£¬25¡Üt¡Ü30\end{array}\right.£¨t¡Ê{N^+}£©$£¬ÇóÈÕÏúÊÛ¶îyµÄ×î´óÖµ£®

²é¿´´ð°¸ºÍ½âÎö>>

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ

4£®Èô¶ÔÈÎÒâx¡ÊR£¬f¡ä£¨x£©=4x3£¬f£¨1£©=-1£¬Ôòf£¨x£©=£¨¡¡¡¡£©
A£®-x4B£®-3x4+2C£®x4-2D£®4x4-5

²é¿´´ð°¸ºÍ½âÎö>>

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÌî¿ÕÌâ

1£®ÈôʵÊýx¡¢yÂú×ãÌõ¼þ$\left\{\begin{array}{l}{x-y+1¡Ý0}\\{x+y-2¡Ý0}\\{x¡Ü1}\end{array}\right.$£¬Ôòlog2£¨2x+y£©µÄ×î´óֵΪ2£®

²é¿´´ð°¸ºÍ½âÎö>>

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ

8£®Èç¹ûʵÊýx£¬yÂú×ãÔ¼ÊøÌõ¼þ$\left\{\begin{array}{l}{2x+y-4¡Ü0}\\{x-y-1¡Ü0}\\{x¡Ý1}\end{array}\right.$£¬Ôòz=3x+2y+$\frac{y}{x}$µÄ×î´óֵΪ£¨¡¡¡¡£©
A£®7B£®8C£®9D£®11

²é¿´´ð°¸ºÍ½âÎö>>

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£º½â´ðÌâ

18£®ÉèÊýÁÐ{an}µÄǰnÏîºÍΪSn£¨n¡ÊN*£©£¬ÇÒÂú×㣺
¢Ù|a1|¡Ù|a2|£»
¢Úr£¨n-p£©Sn+1=£¨n2+n£©an+£¨n2-n-2£©a1£¬ÆäÖÐr£¬p¡ÊR£¬ÇÒr¡Ù0£®
£¨1£©ÇópµÄÖµ£»
£¨2£©ÊýÁÐ{an}ÄÜ·ñÊǵȱÈÊýÁУ¿Çë˵Ã÷ÀíÓÉ£»
£¨3£©ÇóÖ¤£ºµ±r=2ʱ£¬ÊýÁÐ{an}ÊǵȲîÊýÁУ®

²é¿´´ð°¸ºÍ½âÎö>>

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ

5£®ÈôÇúÏßy=lnx+ax2£¨aΪ³£Êý£©²»´æÔÚбÂÊΪ¸ºÊýµÄÇÐÏߣ¬ÔòʵÊýaµÄȡֵ·¶Î§ÊÇ£¨¡¡¡¡£©
A£®£¨-$\frac{1}{2}$£¬+¡Þ£©B£®[-$\frac{1}{2}$£¬+¡Þ£©C£®£¨0£¬+¡Þ£©D£®[0£¬+¡Þ£©

²é¿´´ð°¸ºÍ½âÎö>>

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÌî¿ÕÌâ

2£®ÔÚÒ»¸öÈÝÁ¿Îª5µÄÑù±¾ÖУ¬Êý¾Ý¾ùΪÕûÊý£¬ÒѲâ³öÆäƽ¾ùÊýΪ10£¬µ«Ä«Ë®ÎÛËðÁËÁ½¸öÊý¾Ý£¬ÆäÖÐÒ»¸öÊý¾ÝµÄʮλÊý×Ö1δÎÛË𣬼´9£¬10£¬11£¬£¬ÄÇôÕâ×éÊý¾ÝµÄ·½²îS2¿ÉÄܵÄ×î´óÖµÊÇ$\frac{164}{5}$£®

²é¿´´ð°¸ºÍ½âÎö>>

¿ÆÄ¿£º¸ßÖÐÊýѧ À´Ô´£º ÌâÐÍ£ºÑ¡ÔñÌâ

3£®Ë«ÇúÏß$\frac{y^2}{3}-{x^2}=1$µÄ½¹µã×ø±êÊÇ£¨¡¡¡¡£©
A£®$£¨¡À\sqrt{2}£¬0£©$B£®$£¨0£¬¡À\sqrt{2}£©$C£®£¨0£¬¡À2£©D£®£¨¡À2£¬0£©

²é¿´´ð°¸ºÍ½âÎö>>

ͬ²½Á·Ï°²á´ð°¸