Question

x1+x2-x3=1 2x1+(a+2)x2-(b+2)x3=3

若ax1+x2+x3=2 x1+ax2+x3=2 x1+x2+ax3=2 无解,求a.(a为-2求具体过程)

Answer 1

ax1+x2+x3=2 (1)
x1+ax2+x3=2 (2)
x1+x2+ax3=2 (3)
(1)+(2)+(3)
(a+2)(x1+x2+x3)=6
方程无解,a+2=0
a=-2