It is known that the major axis of the ellipse is three times of the minor axis, and it passes through point a (3,0) and takes the coordinate axis as the axis of symmetry
Suppose the equation is x ^ 2 / m ^ 2 + y ^ 2 / N ^ 2 = 1;
Through the point a (3,0), we can get:
9 / m ^ 2 = 1; m = 3,
The major axis is three times of the minor axis
M / N = 3, or N / M = 3, so:
n=1,or n=9;
So the equation of ellipse is:
x^2/9+y^2=1 or x^2/9+y^/81=1.