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-7подставляем y=5/918*5/9-7==10-7==3