= Y^2 + 2Y - 4Y - 8 + 9 - 6Y + Y^2 - 2 * ( 7Y - 49 + Y^2 - 7Y ) = = 2Y^2 - 8Y + 1 - 2 * ( Y^2 - 49 ) = = 2Y^2 - 8Y + 1 - 2Y^2 + 98 = = - 8Y + 99
Y^2+2y-4y-8+9-6y+^2-(14+2y)(y-7) 4y^2-36y+99=0 дальше сам