Final answer:
The student inquires about the value of k that makes a matrix singular given p = 7, which likely involves calculating the determinant. However, without the specific matrix or additional context, we cannot determine the value of k that meets this condition.
Step-by-step explanation:
The student is asking about conditions for a matrix to be singular. A matrix is considered singular if its determinant is zero. In the context of the information given, particularly with the value of p provided as 7, there is likely additional missing context needed to determine the value of k for which the matrix would be singular. The references to a wave number and boundary conditions suggest this question may relate to advanced topics in mathematics, possibly linear algebra or differential equations in the context of physical phenomena like waves. However, as the actual matrix or its determinant function isn't provided, it is not possible to give a specific value for k without further clarification on the matrix in question.