I am to solve the following using Cramer's rule:

-x1 - 4x2 + 2x3 + x4 = -32

2x1 - x2 + 7x3 + 9x4 = 14

-x1 + x2 + 3x3 + x4 = 11

x1 - 2x2 + x3 - 4x4 = -4

I know x1 = [det(A1)]/[det(A)]

but I'm not sure what the best approach is to find the determinant of a 4x4 matrix, because cofactor expansion takes a very long time, would reducing the matrix to a triangular matrix be the best approach?

Thanks