Question

знайдіть значення виразу 30 балов
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Answer 1

(2ab - b²) / (a² + 3ab)

(a - 2b) / (b - 2a) = 3

a - 2b = 3b - 6a

5b = 7a

b = 7/5a

(2ab - b²) / (a² + 3ab) = b(2a - b) / a(a + 3b) = 7/5a(2a - 7/5a) / a(a + 21/5a) = 7/5a(10/5a - 7/5a) / a(5/5a + 21/5a) = 7/5*3/5a² : a*26/5a² = 21/25 * 5/26 = 21 / 130