This question already has an answer here:
i have the following homework problem:
Find the determinant of X(s):
X(s) = [s, 1, 1, 1], [1, s, 1, 1], [1, 1, s, 1], [1, 1, 1, s]
I know i can exploit the fact that the product of the diagonal gives me the determinant if the matrix is upper, lower or both triangular- but i don't know how i can turn it into a triangular?
If i try regular row operations, i get: X(s) = [s, 1, 1, 1], [0, s-1, 1, 1], [0, 0, s-1, 1], [1-s, 0, 0, s-1]
This is by first subtracting R1 from R2-4, and then subtracting R4 from R2-3. But i can't get any further, how do i solve this?