write the equation for an ellipse with y intercepts (0,-3) and (0,3) and the major axis of length 10.

major axis is 10=2a so that makes a=5.
I believe my equation is
x^2/b^2 + y^2/a^2 = 1
I am assuming b is 3 because of the y-intercept.
so would my answer be
x^2/9 + y^2/25 = 1
Please help. I am confused on how to use the information regarding the y-intercept.
Thank you

Almost,

in standard position the y-intercept is the b value , so you want
x^2/25 + y^2/9 = 1

the standard equation is x^2/a^2 + y^2/b^2 , when the major axis is
along the x-axis
if b>a, then the ellipse would have the major axis along the y-axis.