24y^2-(7y-2)^2+(5y-3)(5y+1) при y=5/9

Question

24y^2-(7y-2)^2+(5y-3)(5y+1)
при y=5/9

Answer 1

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