i-r1,i=2,3,4
2 1 1 1
-1 2 0 0
-1 0 3 0
-1 0 0 4
c1+(1/2)c2+(1/3)c3+(1/4)c4
2+1/2+1/3+1/4 1 1 1
0 2 0 0
0 0 3 0
0 0 0 4
= (2+1/2+1/3+1/4)*2*3*4
= 74.
求线性代数的解答,计算行列式│2111│ │1311│ │1141│ │1115│
i-r1,i=2,3,4
2 1 1 1
-1 2 0 0
-1 0 3 0
-1 0 0 4
c1+(1/2)c2+(1/3)c3+(1/4)c4
2+1/2+1/3+1/4 1 1 1
0 2 0 0
0 0 3 0
0 0 0 4
= (2+1/2+1/3+1/4)*2*3*4
= 74.