Given A and b in Exercises 11 and 12, write the augmented matrix for the linear system that corresponds to the matrix equation Ax = b. Then solve the system and write the solution as a vector. 2 11.A=1 0 1 51,b=1 1 2 11 12. A = 1-3-1 2 | , b= 0 「3-5 4 | and A = 1-2 4 6 1 . Is u in the plane R3 13, Let u = | spanned by the columns of A? Why or why not? Plane spanned by the columns of A is c e u? Where is u?