§ 27: 27.19

27.19 Спростіть вираз:

1) (a13- b13)2a23(a23- b23) • a23b13(a13+ b13)b13(a13- b13) = (a13- b13)2 • a23b13(a13+ b13)a23a13- b13a13+ b13b13(a13- b12) = 1;

2) a-ba12(a14+ b14) • a-ba14a12+ b12(a14- b14) = a-b(a- b)a34a12- b12(a12- b12) = a-b(a-b)a34(a-b) = a-ba34.