What is the sum of 7x^4+ 2xy - 5y^3 and 2x^4 + 3xy + 2y^3?

Which of the following is the result of expanding

Find the equation of the ellipse with the following properties. the ellipse with foci at (0, 6) and (0, -6); y-intercepts (0, 8) and (0, -8).edit: the answer is x^2 over 28 + y^2 over 64 = 1

Factor the polynomial expression x6 – x3 – 20