Simultaneous equations and parameter constraints

Answer: 5

1. The determinant is 20k−100.
2. It is zero at k=5.
3. At that value the left sides are proportional but the right sides are not.

Answer: 5

1. Substitute x=−9 and multiply by−4:−9k+21=−24.
2. Solving gives k=5.

Answer: 5

1. The determinant is 10k−50.
2. It is zero at k=5.
3. At that value the left sides are proportional but the right sides are not.