(a - b)² = a² - 2ab + b² - формула разложения квадрата разности чисел
а = 3 1/3 = 10/3; b = 2 7/9 = 25/9; 1 1/5 = 6/5
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(10/3 - 25/9)² · (6/5)² = 4/9
1) (10/3 - 25/9)² = (10/3)² - 2 · 10/3 · 25/9 + (25/9)² = 100/9 - 500/27 + 625/81 = 900/81 - 1500/81 + 625/81 = 25/81
2) (6/5)² = 6/5 · 6/5 = 36/25
3) 25/81 · 36/25 = (1·4)/(9·1) = 4/9