Locate the foci of ellipse. show your work.
x^2/36 +y^2/11 =1

In this equation, 36>11 and so the ellipse has major axis along x axis
standard equation of ellipse with major axis is along x axis
x^2/a^2+y^2/b^2=1,
the foci are at (ae,0) and (–ae,0)
eccentricity e is given by
ae=√(a^2-b^2)

In this case ae=√(36-11)= √25=+/- 5

Focii are(-5,0) and(5,0)