(2x^3+2x^2+x-8x^4)/(-2x)+x(x-4x^2)]
=2x(x^2+x-4x^3)/(-2x)+x(x-4x^2)
=-(x^2+x-4x^3)+x(x-4x^2)
=-x^2-x+4x^3+x^2-4x^3
=x^2-x^2-x+4x^3-4x^3
=-x