what is the focus of
4x^2-25y^2=100

First - do you recognize that this is te hequatio of a hyperbola?You need to put the equation into the standard form for a hyperbola:


\frac {x^2} {A^2} - \frac {y^2} {B^2} = 1


The focus can then be found from:


C^2 = A^2 + B^2