A=[1,1,0;-2,-1,2;-1,1,0;2,-2,0]
b=[-2;3;-3;2] The system Ax=b has a unique least squares solution u = (x,y,z)
a. Find x,y and z
b. Compute the “least square error” ||\boldsymbol{b}-\boldsymbol{Au}||^2
