How do you find a solution to a matrix $A$ that minimizes $\|x\|$ when $A^TA$ is not invertible? The matrix is $$A = \pmatrix{1 &1&2&2\\1&2&3&4}$$
I don't know if this helps but also in the question above this one, we are asked to find all solutions to $Ax = \pmatrix{0\\11}$
Thank you.