合聚咖

合聚咖

如下行列式咋算

admin

一步一步降阶做:

D5=D4-(1/4)D3 【按r1展开,后面行列式再按c1展开]

=D3-(1/4)D2-(1/4)D3 【D4无疑也等于D3-(1/4)*D2 】

=(3/4)*D3-(1/4)D2

=(3/4)*[D2-(1/4)D1]-(1/4)D2

=(3/4)D2-(3/16)D1-(1/4)D2

=(1/2)D2-(3/16)D1

=(1/2)*(1-1/4)-(3/16)*1

=3/8-3/16

=3/16