Question

Упростить выражение:(y^2-2y)^2-y^2(y+3)(y-3)+2y(2y^2+5)

Answer 1

$<var>(a-b)^{2}=a^{2}-2ab+b^{2}\\\\ (a+b)(a-b)=a^{2}-b^{2}\\\\ (y^{2}-2y)^{2}-y^{2}(y+3)(y-3)+2y(2y^{2}+5)=\\\\ =y^{4}-4y^{3}+4y^{2}-y^{2}(y^{2}-9)+4y^{3}+10y=\\\\ =y^{4}-4y^{3}+4y^{2}-y^{4}+9y^{2}+4y^{3}+10y=13y^{2}+10y=y(13y+10)</var>$