Вправи: 256

256. Подайте у вигляді дробу вираз:

1) ab^–1 + a^–1b = a\ab + b\ba = a2+ b2ab;

2) 3a^–1 + ab^–2 = 3\ba + a\ab2 = 3b2+ a2ab2;

3) m²n²(m^–3 – n^–3) = m²n²(1m3 – 1n3) = m2n21 • n3- m3m3n3 = n3- m3mn;

4) (a + b)^–1 • (a^–1 + b^–1) = 1a+b • (1\ba + 1\ab) = 1a+b • b+aab = 1ab;

5) (c^–2 – d^–2) : (c + d) = (1\d2c2 – 1\a2d2) : (c + d) = d2- c2c2d2 • 1c+d = d-cd+c • 1c2d2(c+d) = d-cc2d2;

6) (xy^–2 + x^–2y) • (x2- xy+ y2x)^–1 = (xy2 + yx2) • xx2- xy+ y2 = x3+ y3y2x2 • xx2- xy+ y2 = x+yx2- xy+ y2 • xx2y2(x2- xy+ y2) = x+yxy2.