Question

Разложите на множители выражение (xy+y^2)(x^2+4x)-(x^2+xy)(y^2+4y)

Answer 1

$(xy+y^2)(x^2+4x)-(x^2+xy)(y^2+4y)=\\\\=y(x+y)\cdot x(x+4)-x(x+y)\cdot y(y+4)=\\\\=(x+y)\Big (yx(x+4)-xy(y+4)\Big )=(x+y)(x^2y+4xy-xy^2-4xy)=\\\\=(x+y)(x^2y-xy^2)=(x+y)\cdot xy(x-y)=xy(x+y)(x-y)$