4• (3+у) • (3 у-1) = (4-5 у) •у

Как решить?

4• (3 + y) (3y - 1) = (4 - 5y) •y

4 (9y - 3 + 3y^2 - y) = 4y - 5y^2

4 (3y^2 + 8y - 3) = 4y - 5y^2

12y^2 + 32y - 12 - 4y + 5y^2 = 0

17y^2 + 28y - 12 = 0

D = 784 + 816 = 1600 = 40^2

y1 = ( - 28 + 40) : 34 = 12/34 = 6/17

y2 = ( - 28 - 40) : 34 = - 68 : 34 = - 2

Ответ 6/17; - 2