Question

1)(y^2-2y)^2-y^2 (y+3)(y-3)+2y(2y^2+5)

Answer 1

$y^4-4y^3+4y^2-y^2(y^2-9)+4y^3+10y=\\=y^4+4y^2-y^4+9y^2+10y=13y^2+10y$

Answer 2

= Y^4 - 4Y^3 + 4Y^2 - Y^2 * ( Y^2 - 9 ) + 4Y^3 + 10Y =
= Y^4 + 4Y^2 + 10Y - Y^4 + 9Y^2 =
= 4Y^2 + 10Y + 9Y^2 =
= 13Y^2 + 10Y