Question

What am I doing wrong, to get a upper triangle matrix. its going to take some time drawing it out. Give me some time.

Answer 1

1

Answer 2

to make the row reduction easier, you could multiply the last row of A by 3
this will change its determinant by a factor of 3, so set k=1/3 to compensate
once you have A in the form of an upper triangular matrix, you can find its determinant by multiplying the entries on its diagonal.
then multiply by 1/3 to get the determinant of the original A matrix