How do I solve this?

For this question, you must enter non-integer numbers as fractions. Do not use decimals. Your neighbour Chelsea wants to find the plane z = ax + by that best fits, in the least squares sense, the following three points. (1, 2, -5), (2, 2, -7), (3, -1, -1) (a) We first assume that all points lie exactly on the plane z = ax + by. In form of matrices, we obtain Ax = z, where x = ("and z = Enter the matrix A in the box below. sin (a) ? (b) We then form the normal equations, Mx = b, for the least squares solution. Enter the matrix M in the box below. sin (a) Ar Enter the vector b, in Maple syntax in the box below. Note: The vector ( ). in Maple syntax, should be entered as