To order the polynomial - x^4y^2+7x^3y^3-3xy^5+2x^2y^4 in descending powers of x, we must take into account the powers of the x. We must start with the term that has the highest degree and end with the term that has the lowest grade.
Finally, when we order the polynomial -x^4y^2+7x^3y^3-3xy^5+2x^2y^4, we get:
-x^4y^2+7x^3y^3+2x^2y^4-3xy^5