Question

What is the size of matrix A?

Answer 1

Swap the 1st and the 2nd rows inversing determinant sign
Divide the 1st row by 54
Multiply the 1st row by 33
Subtract the 1st row from the 3rd row and put the 1st row back as it was
Divide the 2nd row by 12
Multiply the 2nd row by 5
Subtract the 2nd row from the 3rd row and put the second row as it was
Multiply the main diagonal numbers
A= -(54)(12)(-35/12)(0)(0)= 0