the foci of the ellipse given by the equation 100x2 + 25y2 = 2500?

Answer 1

x^2/25 + y^2/100 = 1

the major axis is vertical.
a = 10
b = 5
c^2 = a^2-b^2 = 75

The foci are at (0,±c)

Answer 2

x^2/25+y^2/100=1