text: the way i learned it the standard form of an equation of an ellipse is x^2/a^2 + Y^2/b^2=1\n\nSince x^2 is before y^2 in this problem, the ellipse is horizontal, meaning the major axis is going horizontally. One of the rules of ellipses states that the length of the major axis is 2a units, and the length of the minor axis is 2b units.  therefore, a=9, and b=3 so the equation is x^2/9^2 + y^2/3^2 =1