Question

ÈçͼËùʾ£¬Ä³Ñ§Ð£µÄ½Ìѧ¥ǰÓÐÒ»¿é¾ØÐοյØABCD£¬Æ䳤Ϊ32Ã×£¬¿íΪ18Ã×£¬ÏÖÒªÔÚ´Ë¿ÕµØÉÏÖÖÖ²Ò»¿é¾ØÐβÝƺ£¬Èý±ßÁôÓÐÈËÐеÀ£¬ÈËÐеÀ¿í¶ÈΪaÃ×ÓëbÃ×¾ù²»Ð¡ÓÚ2Ã×£¬ÇÒÒªÇó¡°×ª½Ç´¦£¨Í¼ÖоØÐÎAEFG£©¡±µÄÃæ»ýΪ8ƽ·½Ã×
£¨1£©ÊÔÓÃa±íʾ²ÝƺµÄÃæ»ýS£¨a£©£¬²¢Ö¸³öaµÄÈ¡Öµ·¶Î§
£¨2£©ÈçºÎÉè¼ÆÈËÐеÀµÄ¿í¶Èa¡¢b£¬²ÅÄÜʹ²ÝƺµÄÃæ»ý×î´ó£¿²¢Çó³ö²ÝƺµÄ×î´óÃæ»ý£®
£¨3£©Ö±½Óд³ö£¨²»ÐèÒª¸ø³öÑÝËã²½Ö裩²ÝƺÃæ»ýµÄ×îСֵ¼°´ËʱaµÄÖµ£®

Answer 1

·ÖÎö£º£¨1£©ÓÉÌõ¼þ¿ÉÖªab=8£¬¼´b=

8

a

½áºÏb¡Ý2 ¿ÉÇóaµÄ·¶Î§£¬¶øS£¨a£©=£¨32-2a£©£¨18-b£©=(32-2a)(18-

8

a

)=592-4£¨9a+

64

a

£©£¬
£¨2£©ÀûÓûù±¾²»µÈʽ¿ÉÇó½â9a+

64

a

µÄ×îСֵ£¬½ø¶ø¿ÉÇóSµÄ×î´óÖµ
£¨3£©½áºÏº¯ÊýµÄÐÔÖÊ¿ÉÖª£¬µ±a=4ʱ¿ÉµÃS£¨a£©ÓÐ×îСֵ384m²

½â´ð£º½â£º£¨1£©ÓÉÌõ¼þ¿ÉÖªab=8£¬¼´b=

8

a

¡ßb¡Ý2¡àb=

8

a

¡Ý2£¬Ôòa¡Ü4¡ßa¡Ý2
¡à2¡Üa¡Ü4
S£¨a£©=£¨32-2a£©£¨18-b£©=(32-2a)(18-

8

a

)=592-4£¨9a+

64

a

£©
£¨2£©¡ß9a+

64

a

¡Ý2

9a• 64 a

=48
µ±ÇÒ½öµ±9a=

64

a

¼´a=

8

3

ʱȡµÈºÅ£¬S£¨a£©È¡µÃ×î´óÖµ400m²
£¨3£©µ±a=4ʱS£¨a£©ÓÐ×îСֵ384m²

µãÆÀ£º±¾ÌâÖ÷Òª¿¼²éÁËÀûÓûù±¾²»µÈʽÔÚÇó½âʵ¼ÊÎÊÌâÖеÄ×îÖµµÄÇó½â£¬½âÌâµÄ¹Ø¼üÊÇÒª°ÑÊýѧÎÊÌâת»¯ÎªÊýѧÎÊÌâ½øÐÐÇó½â£®