Which of these is the equation of the directrix of the ellipse x225+y29=1\frac{x^2}{25} + \frac{y^2}{9} = 125x2+9y2=1?
x=±254x = \pm \frac{25}{4}x=±425
x=±425x = \pm \frac{4}{25}x=±254
x=±5x = \pm 5x=±5
x=±3x = \pm 3x=±3