Question

线性代数题目，第三题求大神帮忙求解，要过程，谢谢了

Answer 1

Answer 2

变成5阶行列式
1 0 0 0 0
1 1+a 1 1 1
1 1 1-a 1 1
1 1 1+b 1 1
1 1 1 1 1-b
=
1 -1 -1 -1 -1
1 a 0 0 0
1 0 -a 0 0
1 0 0 b 0
10 0 0 -b
按最后一行展开
=a^2b^2+a^2b
=a^2b(1+b)