Question

9£®ÌìË®ÊÐijÆóÒµ½Óµ½Ò»ÅúôÕ×ÓÉú²úÈÎÎñ£¬°´ÒªÇóÔÚ19ÌìÄÚÍê³É£¬Ô¼¶¨ÕâÅúôÕ×ӵijö³§¼ÛΪÿֻ4Ôª£¬Îª°´Ê±Íê³ÉÈÎÎñ£¬¸ÃÆóÒµÕÐÊÕÁËй¤ÈË£¬Éèй¤ÈËÀîºìµÚxÌìÉú²úµÄôÕ×ÓÊýÁ¿ÎªyÖ»£¬yÓëxÂú×ãÈçϹØϵ£ºy=$\left\{\begin{array}{l}{32x£¨0¡Üx¡Ü5£©}\\{20x+60£¨5£¼x¡Ü19£©}\end{array}\right.$
£¨1£©ÀîºìµÚ¼¸ÌìÉú²úµÄôÕ×ÓÊýÁ¿Îª260Ö»£¿
£¨2£©Èçͼ£¬ÉèµÚxÌìÉú²úµÄÿֻôÕ×ӵijɱ¾ÊÇpÔª£¬pÓëxÖ®¼äµÄ¹Øϵ¿ÉÓÃͼÖеĺ¯ÊýͼÏóÀ´¿Ì»­£¬ÈôÀîºìµÚxÌì´´ÔìµÄÀûÈóΪwÔª£¬ÇówÓëxÖ®¼äµÄº¯Êý±í´ïʽ£¬²¢Çó³öµÚ¼¸ÌìµÄÀûÈó×î´ó£¿×î´óÀûÈóÊǶàÉÙÔª£¿£¨ÀûÈó=³ö³§¼Û-³É±¾£©

Answer 1

·ÖÎö £¨1£©ÁÊýy=20x+60µÄº¯ÊýֵΪ260£¬È»ºóÇó¶ÔÓ¦µÄ×Ô±äÁ¿µÄÖµ¼´¿É£»
£¨2£©ÏÈÀûÓú¯ÊýͼÏóµÃµ½PÓëxµÄ¹Øϵ£º0¡Üx¡Ü9ʱ£¬p=2£»£¬µ±9£¼x¡Ü19ʱ£¬½âÎöʽΪy=$\frac{1}{10}$x+$\frac{11}{10}$£¬È»ºó·ÖÀàÌÖÂÛ£ºµ±0¡Üx¡Ü5ʱ£¬w=£¨4-2£©•32x£»µ±5£¼x¡Ü9ʱ£¬w=£¨4-2£©•£¨20x+60£©£»µ±9£¼x¡Ü19ʱ£¬w=[4-£¨$\frac{1}{10}$x+$\frac{11}{10}$£©]•£¨20x+60£©£¬ÔÙÀûÓÃÒ»´Îº¯ÊýºÍ¶þ´Îº¯ÊýµÄÐÔÖÊÇó³öÈýÖÖÇé¿öϵÄwµÄ×î´óÖµ£¬ÓÚÊDZȽϴóС¼´¿ÉµÃµ½ÀûÈóµÄ×î´óÖµ£®

½â´ð ½â£º£¨1£©ÉèÀîºìµÚxÌìÉú²úµÄôÕ×ÓÊýÁ¿Îª260Ö»£¬
¸ù¾ÝÌâÒâµÃ20x+60=260£¬½âµÃx=10£¬
´ð£ºÀîºìµÚ10ÌìÉú²úµÄôÕ×ÓÊýÁ¿Îª260Ö»£»
£¨2£©¸ù¾ÝͼÏóµÃµ±0¡Üx¡Ü9ʱ£¬p=2£»
µ±9£¼x¡Ü19ʱ£¬Éè½âÎöʽΪy=kx+b£¬
°Ñ£¨9£¬2£©£¬£¨19£¬3£©´úÈëµÃ$\left\{\begin{array}{l}{9k+b=2}\\{19k+b=3}\end{array}\right.$£¬½âµÃ$\left\{\begin{array}{l}{k=\frac{1}{10}}\\{b=\frac{11}{10}}\end{array}\right.$£¬
ËùÒÔp=$\frac{1}{10}$x+$\frac{11}{10}$£¬
¢Ùµ±0¡Üx¡Ü5ʱ£¬w=£¨4-2£©•32x=64x£¬x=5ʱ£¬´ËʱwµÄ×î´óֵΪ320£¨Ôª£©£»
¢Úµ±5£¼x¡Ü9ʱ£¬w=£¨4-2£©•£¨20x+60£©=40x+120£¬x=9ʱ£¬´ËʱwµÄ×î´óֵΪ480£¨Ôª£©£»
¢Ûµ±9£¼x¡Ü19ʱ£¬w=[4-£¨$\frac{1}{10}$x+$\frac{11}{10}$£©]•£¨20x+60£©=-2x²+52x+174=-2£¨x-13£©²+512£¬x=13ʱ£¬´ËʱwµÄ×î´óֵΪ512£¨Ôª£©£»
×ÛÉÏËùÊö£¬µÚ13ÌìµÄÀûÈó×î´ó£¬×î´óÀûÈóÊÇ512Ôª£®

µãÆÀ ±¾Ì⿼²éÁ˶þ´Îº¯ÊýµÄÓ¦Ó㺽â´ËÀàÌâµÄ¹Ø¼üÊÇͨ¹ýÌâÒ⣬ȷ¶¨³ö¶þ´Îº¯ÊýµÄ½âÎöʽ£¬È»ºóÈ·¶¨Æä×î´óÖµ£¬Êµ¼ÊÎÊÌâÖÐ×Ô±äÁ¿xµÄȡֵҪʹʵ¼ÊÎÊÌâÓÐÒâÒ壬Òò´ËÔÚÇó¶þ´Îº¯ÊýµÄ×îֵʱ£¬Ò»¶¨Òª×¢Òâ×Ô±äÁ¿xµÄÈ¡Öµ·¶Î§£®