Find the determinant of a 3x3 square matrix

We can expand following any row or column we want. A wise choice would be to use a row/column in which we have one or more zero entries to reduce the calculations. From this, we pick the first entry on the chosen row/column and multiply it by the determinant of the matrix given by the entries not in either the row/column we chose. We then add the negative of the product between the second entry in our row/column and the determinant of the matrix left (as in the previous step). Finally we add the (positive) product between the last entry and the determinant of the (in this case) 2x2 matrix given.