(y^4+y^3)(y^2-y)=y^3(y^2+1)(y-1)

(y^4+y^3)(y^2-y)=y^3(y^2+1)(y-1)
y^3(y+1)y(y-1)=y^3(y^2+1)(y-1)
y(y+1)=y^2+1
y^2+y=y^2+1
y=1
Ответ: y=1