For what value of k does the system below not have a unique solution?

-1x + 7y + 2z = 6
2x + 1y + kz = -11
3x - 6y - 2z = -25

A.5
B.0
C.-2
D.-8

1 answer

determinant = 2+21k-24-6-6k+28
If the determinant is zero, we can not solve for the variables
0 +15 k = 0
k = 0