Question 416231
The standard form for an ellipse is {{{x^2/a^2 + y^2/b^2 = 1}}}
The major axis goes from (-a,a).
Since 25=5^2, the x intercepts are x=-5, x=5.
Another way to see this is to set y=0 in the equation for the ellipse.
Then we have {{{x^2/25 = 1}}} -> {{{x^2 = 25}}}.  The two solutions are -5,5.