A matrix is singular if and only if its determinate equals 0.
Ya know how to find the determinate of a 3x3 matrix?
EDIT: Just saw your edit.
For which two complex values of s is C singular?
a) What is meant by the term singular? Is it just ones across the matrix or something else entirely?
b) How do I begin to work it out, what steps should I take?
EDIT: I understand it now but thanks to anyone who attempted it for me