Ò»¡¢Ñ¡ÔñÌâ 1£®ÉèÈ«¼¯u=z£¬¼¯ºÏ £¬Ôò¼¯ºÏ Ϊ £¨ £© a£®{1£¬2} b£®{1} c£®{2} d£®{-1£¬1} 2£®º¯Êý µÄ·´º¯ÊýΪ £¨ £© a£® b£® c£® d£® 3£®Èô £¬Ôòm= £¨ £© a£® b£® c£®2 d£®-2