`Answer:`
\( B=-4x^5.y+x^4.y^3-3x^2.y^3.z^2+4.x^5.y-2.y^4-x^4.y-x^4.y+3.y^4+4.y^2.x^2.z^2-y^4+\frac{1}{2}\)
\(=-4x^5y-3x^2y^3z^2+4x^y-2y^4+3y^4+4x^2y^3z^2-y^4+\frac{1}{2}\)
\(=-4x^5y+x^2y^3z^2+4x^y-2y^4+3y^4-y^4+\frac{1}{2}\)
\(=-4x^5y+x^2y^3z^2+4x^y+\frac{1}{2}\)