Question

What is the constant sum of the ellipse with foci at (-12, 0) and (12, 0) that passes through the point (-15, 0)?

Answer 1

constant sum ?

you mean equation of the ellipse...

Answer 2

constant sum. That's what the equation gives me

Answer 3

looks like major vertices are at (-15,0) , (15,0)

a = 15
c = 12

a^2 = b^2 + c^2
225 = b^2 + 144
b = 9
equation:
\[\frac{x^{2}}{225}+\frac{y^{2}}{81} = 1\]