I am trying to solve this, but I am stuck....
1 2 -1
2 3 c
0 c -15
1 2 -1
0 -1 (2+c)
0 c -15
1 2 -1
0 1 (-2)-c))
0 1/15c 1
Hello, mathproblems!
Your method should work if you know what to look for.
(But from your responses, I'm not sure you do.)
We have: .
A matrix is not invertible if an entire row is composed of zeros.
That is: .
Therefore: .