ÌâÄ¿ÄÚÈÝ
ij¹«Ë¾ÓмÛÖµaÍòÔªµÄÒ»ÌõÁ÷Ë®Ïߣ¬ÒªÌá¸ß¸ÃÁ÷Ë®ÏßµÄÉú²úÄÜÁ¦£¬¾ÍÒª¶ÔÆä½øÐм¼Êõ¸ÄÔ죬´Ó¶øÌá¸ß²úÆ·¸½¼ÓÖµ£¬¸ÄÔìÐèҪͶÈ룬¼ÙÉ踽¼ÓÖµyÍòÔªÓë¼¼Êõ¸ÄÔìͶÈëxÍòÔªÖ®¼äµÄ¹ØϵÂú×㣺
¢ÙyÓë2a-xºÍx-aµÄ³Ë»ý³ÉÕý±È£»¢Úx=
ʱ£¬y=a2£»¢Ûy£¾0£®
£¨I£©Éèy=f£¨x£©£¬Çóf£¨x£©±í´ïʽ£¬²¢Çóy=f£¨x£©µÄ¶¨ÒåÓò£»
£¨II£©ÇóÿÍòÔª¼¼Êõ¸ÄÔìͶÈëËù»ñµÃµÄƽ¾ù¸½¼ÓÖµµÄ×î´óÖµ£¬²¢Çó³ö´ËʱµÄ¼¼Êõ¸ÄÔìͶÈ룮
¢ÙyÓë2a-xºÍx-aµÄ³Ë»ý³ÉÕý±È£»¢Úx=
3a | 2 |
£¨I£©Éèy=f£¨x£©£¬Çóf£¨x£©±í´ïʽ£¬²¢Çóy=f£¨x£©µÄ¶¨ÒåÓò£»
£¨II£©ÇóÿÍòÔª¼¼Êõ¸ÄÔìͶÈëËù»ñµÃµÄƽ¾ù¸½¼ÓÖµµÄ×î´óÖµ£¬²¢Çó³ö´ËʱµÄ¼¼Êõ¸ÄÔìͶÈ룮
·ÖÎö£º£¨I£©Éèy=k£¨2a-x£©£¨x-a£©£¬ÀûÓõ±x=
ʱ£¬y=a2£¬¿ÉÇók=4£¬´Ó¶ø¿ÉµÃº¯Êý±í´ïʽ£¬¼´¿ÉÇóµÃy=f£¨x£©µÄ¶¨ÒåÓò£»
£¨II£©È·¶¨Ã¿ÍòÔª¼¼Êõ¸ÄÔìͶÈ뺯Êý½âÎöʽ£¬ÀûÓûù±¾²»µÈʽ£¬¼´¿ÉÇóµÃ½áÂÛ£®
3a |
2 |
£¨II£©È·¶¨Ã¿ÍòÔª¼¼Êõ¸ÄÔìͶÈ뺯Êý½âÎöʽ£¬ÀûÓûù±¾²»µÈʽ£¬¼´¿ÉÇóµÃ½áÂÛ£®
½â´ð£º½â£º£¨I£©Éèy=k£¨2a-x£©£¨x-a£©£¬
ÒòΪµ±x=
ʱ£¬y=a2£¬ËùÒÔk=4
ËùÒÔy=4£¨2a-x£©£¨x-a£©
ÒòΪ4£¨2a-x£©£¨x-a£©£¾0£¬ËùÒÔa£¼x£¼2a
ËùÒÔ¶¨ÒåÓòΪ£¨a£¬2a£©£»
£¨II£©
=-4£¨x+
£©+12a¡Ü-4•2
+12a=(12-8
)a
µ±ÇÒ½öµ±x=
£¬¼´x=
aʱ£¬Ã¿ÍòÔª¼¼Êõ¸ÄÔìͶÈëËù»ñµÃµÄƽ¾ù¸½¼ÓÖµµÄ×î´ó£®
ÒòΪµ±x=
3a |
2 |
ËùÒÔy=4£¨2a-x£©£¨x-a£©
ÒòΪ4£¨2a-x£©£¨x-a£©£¾0£¬ËùÒÔa£¼x£¼2a
ËùÒÔ¶¨ÒåÓòΪ£¨a£¬2a£©£»
£¨II£©
y |
x |
2a2 |
x |
x•
|
2 |
µ±ÇÒ½öµ±x=
2a2 |
x |
2 |
µãÆÀ£º±¾Ì⿼²éº¯Êý½âÎöʽµÄÈ·¶¨£¬¿¼²é»ù±¾²»µÈʽµÄÔËÓ㬿¼²éѧÉúµÄ¼ÆËãÄÜÁ¦£¬ÊôÓÚÖеµÌ⣮

Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿