Step 1: Analyze the system of equations.
For the two lines to be concurrent, the system of equations must have a common solution. This happens when \( \ell = m = n = 0 \).
Step 2: Conclusion.
The lines are concurrent when \( \ell = m = n = 0 \).
Final Answer:
\[
\boxed{\ell = m = n = 0}
\]