Science:Math Exam Resources/Courses/MATH152/April 2013/Question A 11/Hint 3

Another solution attempt can be given by only looking at the first two columns of B: ${\tilde {B}}={\begin{bmatrix}1&0\\-3&1\end{bmatrix}}$.

Then, find the matrix inverse of ${\tilde {B}}$ and add a row of zeros to that inverse matrix you found.