Question

ij²úÆ·Éú²ú³§¼Ò¸ù¾ÝÒÔÍùµÄÉú²úÏúÊÛ¾­ÑéµÃµ½ÏÂÃæÓйØÉú²úÏúÊÛµÄͳ¼Æ¹æÂÉ£ºÃ¿Éú²ú²úÆ·x£¨°Ų̀£©£¬Æä×ܳɱ¾ÎªG£¨x£©£¨ÍòÔª£©£¬ÆäÖй̶¨³É±¾Îª2.8ÍòÔª£¬²¢ÇÒÿÉú²ú1°Ų̀µÄÉú²ú³É±¾Îª1ÍòÔª£¨×ܳɱ¾=¹Ì¶¨³É±¾+Éú²ú³É±¾£©£®ÏúÊÛÊÕÈëR£¨x£©£¨ÍòÔª£©Âú×ãR(x)=

-0.4x2+4.2x(0¡Üx¡Ü5) 11£¬(x£¾5)

£¬¼Ù¶¨¸Ã²úÆ·²úÏúƽºâ£¨¼´Éú²úµÄ²úÆ·¶¼ÄÜÂôµô£©£¬¸ù¾ÝÉÏÊöͳ¼Æ¹æÂÉ£¬ÇëÍê³ÉÏÂÁÐÎÊÌ⣺
£¨1£©Ð´³öÀûÈóº¯Êýy=f£¨x£©µÄ½âÎöʽ£¨ÀûÈó=ÏúÊÛÊÕÈë-×ܳɱ¾£©£»
£¨2£©¹¤³§Éú²ú¶àÉŲ̀²úƷʱ£¬¿ÉʹӯÀû×î¶à£¿

Answer 1

·ÖÎö£º£¨1£©ÓÉÌâÒâµÃG£¨x£©=2.8+x£®ÓÉR(x)=

-0.4x2+4.2x(0¡Üx¡Ü5) 11£¬(x£¾5)

£¬f£¨x£©=R£¨x£©-G£¨x£©£¬ÄÜд³öÀûÈóº¯Êýy=f£¨x£©µÄ½âÎöʽ£®
£¨2£©µ±x£¾5ʱ£¬Óɺ¯Êýf£¨x£©µÝ¼õ£¬Öªf£¨x£©£¼f£¨5£©=3.2£¨ÍòÔª£©£®µ±0¡Üx¡Ü5ʱ£¬º¯Êýf£¨x£©=-0.4£¨x-4£©²+3.6£¬µ±x=4ʱ£¬f£¨x£©ÓÐ×î´óֵΪ3.6£¨ÍòÔª£©£®ÓÉ´ËÄÜÇó³ö¹¤³§Éú²ú¶àÉŲ̀²úƷʱ£¬¿ÉʹӯÀû×î¶à£®

½â´ð£º½â£º£¨1£©ÓÉÌâÒâµÃG£¨x£©=2.8+x£®¡­£¨2·Ö£©
¡ßR(x)=

-0.4x2+4.2x(0¡Üx¡Ü5) 11£¬(x£¾5)

£¬
¡àf£¨x£©=R£¨x£©-G£¨x£©
=

-0.4x2+3.2x-2.8(0¡Üx¡Ü5) 8.2-x(x£¾5)

£®¡­£¨7·Ö£©
£¨2£©µ±x£¾5ʱ£¬
¡ßº¯Êýf£¨x£©µÝ¼õ£¬
¡àf£¨x£©£¼f£¨5£©=3.2£¨ÍòÔª£©£®¡­£¨10·Ö£©
µ±0¡Üx¡Ü5ʱ£¬º¯Êýf£¨x£©=-0.4£¨x-4£©²+3.6£¬
µ±x=4ʱ£¬f£¨x£©ÓÐ×î´óֵΪ3.6£¨ÍòÔª£©£®¡­£¨14·Ö£©
ËùÒÔµ±¹¤³§Éú²ú4°Ų̀ʱ£¬¿ÉʹӮÀû×î´óΪ3.6ÍòÔª£®¡­£¨15·Ö£©

µãÆÀ£º±¾Ì⿼²éº¯Êý֪ʶÔÚÉú²úʵ¼ÊÖеľßÌåÓ¦Ó㬽âÌâʱҪÈÏÕæÉóÌ⣬×Ðϸ½â´ð£¬×¢ÒâÍÚ¾òÌâÉèÖеÄÒþº¬Ìõ¼þ£¬ºÏÀíµØ½øÐеȼÛת»¯£®