Question

Find the coordinates of the foci for the ellipse:

(x + 3)2/9 + (y - 1)2/25 = 1

Answer 1

I think you have a typo. What you have written is a linear equation, not an ellipse. Can you write it in the form of the following please? This isn't logical as written, sorry.
\[(x/a)^2+(x/b)^2=1\]
(a & b are constants)

If you can do that then you can find the focus using one of the following (remember the E mean's eccentricity, whereas a is the longer radius and b is the shorter radius, radius from the center/centroiod that is):
\[f=a *\epsilon=\sqrt{a^2-b^2}\]

I believe this should get you toward finding your answer ;-)

Answer 2

(x+3)^(2)/(9)+(y-1)^(2)/(25)=1

Answer 3

(-3, -3) and (-3, 5) as seen here: