i1+i2-i3=0 i1+4i3=18 i2+4i3=9 求 i1 i2 i3
问题描述：
i1+i2-i3=0 i1+4i3=18 i2+4i3=9 求 i1 i2 i3
答
i1+i2-i3=0 ```````````````1i1+4i3=18 ```````````````2i2+4i3=9 ````````````````3由2式－3式得：i1-i2=9 ·······················4由1式x4+2式得：5i1+4i2=18·············...