qr-factorization code snippets in matlab

given the matrix a=magic(3), compute its qr factorization and solve the linear system qx=b, with b=[1,2,3]^t. the solution is, approximately: in matlab

given the matrix a=magic(3), compute its qr factorization and solve the linear system rx=b, with b=[1,2,3]^t. the solution is, approximately: in matlab