24y^2-(7y-2)^2+(5y-3)(5y+1) при y=5/9

24y^2-(7y-2)^2+(5y-3)(5y+1)= =24y^2-(49y^2+4-28y)+25y^2+5y-15y-3= =24y^2-49y^2-4+28y+25y^2+5y-15y-3= =-7+18y= =18y-7 подставляем y=5/9 18*5/9-7= =10-7= =3