( y + 4 ) / ( y + 5 ) - ( 2y - 8 ) / ( y - 5 ) = 10 / ( y^2 - 25 )
y ≠ -5 ; y ≠ 5
( y + 4 )( y - 5 ) - ( 2y - 8 )( y + 5 ) = 10
y^2 - 5y + 4y - 20 - ( 2y^2 + 10y - 8y - 40 ) = 10
y^2 - y - 20 - 2y^2 - 2y + 40 - 10 = 0
- y^2 - 3y + 10 = 0
y^2 + 3y - 10 = 0
D = 9 + 40 = 49 = 7^2
y1 = ( - 3 + 7 ) : 2 = 2
y2 = ( - 3 - 7 ) : 2 = - 5 ( не подходит )
ОТВЕТ 2