Hi, I desperately need help on this machine learning question on optimization and gradients. Any help on any of the steps would really be appreciated!

6 Gradient Descent Consider the optimization problem minx Ax - b'x, where A e Rnxn is a PSD matrix with 0 0 close to x*, i.e. || _(K) x*ll2 0 close to x*, i.e. || _(K) x*ll2