найдите значение выражения m^2+mn-2n^2/2m^2-5mn+3n^2 при m/n=2/3

M/n=2/3 ⇔n=3m/2

(m²+mn-2n²) / (2m²-5mn+3n²) = (m²+m * (3m/2) - 2 (3m/2) ²) / (2m²-5m (3m/2) + 3 (3m/2) ²) =

(m² + (3m²/2) - (9m²/2)) / (2m² - (15m²/2) + (27m²/4)) = - 2m² / (5m²/4) = - 8/5=-1.6

отв:-1.6