Find the rank of the following matrix:
1 3 -6 5
2 -1 0 3
-5 -15 30 -25

I usually work out ranks by finding the determinant and reducing the size of the square matrix when the determinant equals zero, but I cannot find the determinant here so am stuck!

Question

Find the rank of the following matrix:
1   3  -6   5
2  -1   0   3
-5 -15  30 -25

I usually work out ranks by finding the determinant and reducing the size of the square matrix when the determinant equals zero, but I cannot find the determinant here so am stuck!

anonymous · Answer

Do you know cofactor expansion? For solving the determinant of a 3x3 say?

anonymous · Answer

Yes, I believe so (not great with the names of methods)
I find that when remove a column or row in this case, I'm left with a 2x3 leaving me with the same problem.