2/3 ab² + 1/7 a²b + 1/6 b²a - 4/7 ba² = 2/3 ab² + 1/6 b²a + 1/7 a²b - 4/7 ba² = 2/3 ab² + 1/6 ab² + 1/7 a²b - 4/7 a²b = (2/3 + 1/6)ab² + (1/7 - 4/7)a²b = (4/6 + 1/6)ab² + (-3/7)a²b = 5/6 ab² - 3/7 a²b
Ответ: 5/6 ab² - 3/7 a²b