Using the notation of Section 16.1, write the models [A0][A1][C],

[A0][A1][C] A21 = A31, and [A0][A1][C] A21 = A31,A20 = A30 in matrix form. (Hint: To obtain

[A0][A1][C] A21 = A31 from [A0][A1][C], replace the two columns of X corresponding to A21 and A31 with one column consisting of their sum.) Use a regression program to fit these three models. (Hint:

Eliminate the intercept, and to impose the side conditionC1 = 0, drop the column corresponding to C1.)