a+8b+27c=216.(1)
a+b+c=49.(2)
(1)-(2)
7b-26c=167
b=1/7(167+26c).(3)
(1)-8*(2)
a+8b+27c-8a-8b-8c=216-8*49
-7a+19c=-176
a=1/7(176+19c).(4)
(3),(4)带入(2)
会做了么?
a+8b+27c=216.(1)
a+b+c=49.(2)
(1)-(2)
7b-26c=167
b=1/7(167+26c).(3)
(1)-8*(2)
a+8b+27c-8a-8b-8c=216-8*49
-7a+19c=-176
a=1/7(176+19c).(4)
(3),(4)带入(2)
会做了么?