Let the length of a latus rectum of an ellipse
$
\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1
$
be 10. If its eccentricity is $ e $, and the minimum value of the function $ f(t) = t^2 + t + \frac{11}{12} $, where $ t \in \mathbb{R} $, then $ a^2 + b^2 $ is equal to: