Question

9£®ÒÑÖª·½³Ì×é$\left\{\begin{array}{l}{3x+7y+z=3.15}\\{4x+10y+z=4.20}\end{array}\right.$£¬Çóx+y+zµÄÖµ£®
½â£º½«Ô­·½³Ì×éÕûÀíµÃ
$\left\{\begin{array}{l}{2£¨x+3y£©+£¨x+y+z£©=3.15£¬¢Ù}\\{3£¨x+3y£©+£¨x+y+z£©=4.20£¬¢Ú}\end{array}\right.$
¢Ù¡Á3£¬µÃ6£¨x+3y£©+3£¨x+y+x£©=9.45£¬¢Û
¢Ú¡Á2£¬µÃ6£¨x+3y£©+2£¨x+y+z£©=8.40£¬¢Ü
¢Û-¢Ü£¬µÃx+y+z=1.05£®
·ÂÕÕÉÏÊö½â·¨£¬ÒÑÖª·½³Ì×é$\left\{\begin{array}{l}{x+y+z=11}\\{x-3y-z=1}\end{array}\right.$
ÊÔÇóx+0.5zµÄ½â£®

Answer 1

·ÖÎö °Ñx+0.5z¿´³ÉÒ»¸öÕûÌ壬Àà±ÈÌâ¸É½â·¨¼´¿ÉÇó³ö´ð°¸£®

½â´ð ½â£º¸ù¾ÝÌâÒ⣬µÃ£¬
½«Ô­·½³Ì×éÕûÀíµÃ£¬$\left\{\begin{array}{l}{£¨x+0.5z£©+£¨y+0.5z£©=11¢Ù}\\{£¨x+0.5z£©-3£¨y+0.5z£©=1¢Ú}\end{array}\right.$
¢Ù¡Á3-¢ÚµÃ£¬4£¨x+0.5z£©=34£¬
½âµÃx+0.5z=$\frac{17}{2}$£®

µãÆÀ ±¾ÌâÖ÷Òª¿¼²éÁ˽âÈýÔªÒ»´Î·½³Ì×éµÄ֪ʶ£¬½âÌâµÄ¹Ø¼üÊÇÀûÓÃÕûÌå·¨½â·½³Ì×飬´ËÌâÄѶȲ»´ó£®