Question

请问方程组求解怎么求，求a，b，c，谢谢

Answer 1

∵r[(1,2,1)(0,-1,-1)(3,4,1)]=2
∴r[(1,2,1,3)(0,-1,-1,b)(3,4,1,7)]=2
【方程有解，增广矩阵的秩等于系数矩阵的秩】
=>
所有可能的三阶行列式为0
=>
b=-1
【
|(2,1,3)(-1,-1,b)(4,1,7)|=0
=>
|(2,1,3)(1,0,b+3)(2,0,4)|=0
=>
(-1)*|(1,b+3)(2,4)|=0
=>
(-1)*[4-2(b+3)]=0
=>
2b+2=0
=>
b=-1
】